diff --git a/postfix/HISTORY b/postfix/HISTORY
index 6411c45db..959e0fa34 100644
--- a/postfix/HISTORY
+++ b/postfix/HISTORY
@@ -27945,9 +27945,9 @@ Apologies for any names omitted.
 
 20240229
 
-	Clenup: moved the new DNS_RR.flags structure member to the
-	location of a "padding" hole (two bytes for ILP32 systems,
-	6 bytes for LP64). File: dns/dns.h.
+	Compatibility: moved the new DNS_RR.flags structure member
+	to the location of a "padding" hole (two bytes for ILP32
+	systems, 6 bytes for LP64). File: dns/dns.h.
 
 	Deprecation: removed permit_naked_ip_address, reject_maps_rbl,
 	and check_relay_domains. These have been logging deprecation
@@ -27956,3 +27956,20 @@ Apologies for any names omitted.
 	Files: smtpd/smtpd_check.c, smtpd/smtpd_check_backup.ref,
 	smtpd/smtpd_exp.ref, smtpd/smtpd_deprecated.in,
 	smtpd/smtpd_deprecated.ref.
+
+20240302
+
+	Cleanup: fixed inconsistent formatting of deprecation warning
+	messages. Files: postconf/postconf_unused.c, postconf/test76.ref,
+	smtpd/smtpd_check.
+
+	Documentation: DEPRECATION_README suggests replacements for
+	features that will be removed or than have been removed.
+	Files: proto/DEPRECATION_README.html, conf/postfix-files,
+	html/index.html, proto/Makefile.in.
+
+20240305
+
+	Documentation: in the master.cf documentation, added text
+	for "quoting" a command-line argument that starts with "{".
+	File: proto/master.
diff --git a/postfix/README_FILES/AAAREADME b/postfix/README_FILES/AAAREADME
index 6bef06dec..94d552ece 100644
--- a/postfix/README_FILES/AAAREADME
+++ b/postfix/README_FILES/AAAREADME
@@ -15,6 +15,7 @@ GGeenneerraall ccoonnffiigguurraattiioonn
   * SMTPUTF8_README: SMTPUTF8 Support
   * MAILLOG_README: Postfix logging to file or stdout
   * COMPATIBILITY_README: Backwards-Compatibility Safety Net
+  * DEPRECATION_README: Deprecated features and alternatives
   * INSTALL: Installation from source code
 
 PPrroobblleemm ssoollvviinngg
diff --git a/postfix/README_FILES/DEPRECATION_README b/postfix/README_FILES/DEPRECATION_README
new file mode 100644
index 000000000..87cf2474f
--- /dev/null
+++ b/postfix/README_FILES/DEPRECATION_README
@@ -0,0 +1,270 @@
+PPoossttffiixx RReeppllaacceemmeennttss ffoorr DDeepprreeccaatteedd FFeeaattuurreess
+
+-------------------------------------------------------------------------------
+
+PPuurrppoossee ooff tthhiiss ddooccuummeenntt
+
+This document describes Postfix features that are deprecated (will be removed)
+or that have already been removed. It also has tips for making an existing
+Postfix configuration more future-proof.
+
+Overview:
+
+  * Why deprecate?
+  * Deprecation process
+  * Deprecated features
+
+WWhhyy ddeepprreeccaattee??
+
+Sometimes, a Postfix feature needs to be replaced with a different one. To give
+an example:
+
+  * The initial Postfix TLS implementation used multiple boolean parameters:
+    one parameter to enable opportunistic TLS (for example, "smtp_enforce_tls =
+    yes") and one parameter to enable mandatory TLS (for example,
+    "smtp_require_tls = yes").
+
+  * As we added support more features such as fingerprint, dane, and so on, we
+    decided not to add more boolean parameters. Instead we introduced one
+    configuration parameter to select from multiple deployment models (for
+    example, smtp_tls_security_level = may | encrypt | dane, etc...).
+
+Having both the "old" and "new" way to configure Postfix is convenient for
+existing Postfix installations, because their configuration does not break
+after an upgrade to a new version. Unfortunately, there are also disadvantages.
+Having multiple ways to do similar things is not only confusing for newcomers,
+it also makes Postfix harder to change.
+
+DDeepprreeccaattiioonn pprroocceessss
+
+The basic process steps are:
+
+ 1. Inform humans that a feature will be removed, and suggest replacements, in
+    logging and documentation.
+
+ 2. Remove the feature, and update logging and documentation.
+
+Disclaimer: it has taken 20 years for some features to be removed. This past is
+not a guarantee for the future.
+
+DDeepprreeccaatteedd ffeeaattuurreess
+
+The table summarizes removed or deprecated features and replacements. Click on
+the "obsolete feature" name for a more detailed description.
+
+     _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
+    |                           |WWaarrnniinngg|          |                         |
+    |OObbssoolleettee ffeeaattuurree nnaammee      |aass     |RReemmoovveedd   |RReeppllaacceemmeenntt              |
+    |                           |ooff     |iinn vveerrssiioonn|                         |
+    |                           |vveerrssiioonn|          |                         |
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+    |disable_dns_lookups        |   3.9 |      -   |smtp_dns_support_level   |
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+    |xxx_use_tls                |   3.9 |      -   |xxx_tls_security_level   |
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+    |xxx_enforce_tls            |   3.9 |      -   |xxx_tls_security_level   |
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+    |xxx_per_site               |   3.9 |      -   |xxx_policy_maps          |
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+    |smtpd_tls_dh1024_param_file|   3.9 |      -   |do not specify (leave at |
+    |                           |       |          |default)                 |
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+    |smtpd_tls_eecdh_grade      |   3.9 |      -   |do not specify (leave at |
+    |                           |       |          |default)                 |
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+    |permit_mx_backup           |   3.9 |      -   |relay_domains            |
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+    |check_relay_domains        |   2.2 |     3.9  |permit_mynetworks,       |
+    |                           |       |          |reject_unauth_destination|
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+    |reject_maps_rbl            |   2.1 |     3.9  |reject_rbl_client        |
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+    |permit_naked_ip_address    |   2.0 |     3.9  |permit_mynetworks,       |
+    |                           |       |          |permit_sasl_authenticated|
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+
+OObbssoolleettee DDNNSS oonn//ooffff ccoonnffiigguurraattiioonn
+
+The postconf(1) command logs the following:
+
+  * support for parameter "disable_dns_lookups" will be removed; instead,
+    specify "smtp_dns_support_level"
+
+Replace obsolete configuration with its replacement:
+
+     _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
+    |GGooaall                  |OObbssoolleettee ccoonnffiigguurraattiioonn  |RReeppllaacceemmeenntt             |
+    |                      |                        |ccoonnffiigguurraattiioonn           |
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+    |To disable DNS lookups|disable_dns_lookups =   |smtp_dns_support_level =|
+    |in the Postfix SMTP/  |yes                     |disabled                |
+    |LMTP client           |                        |                        |
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+    |                      |                        |Leave                   |
+    |                      |                        |smtp_dns_support_level  |
+    |To enable DNS lookups |                        |at the implicit default |
+    |in the Postfix SMTP/  |disable_dns_lookups = no|which is empty, unless  |
+    |LMTP client           |                        |you need a higher       |
+    |                      |                        |support level such as   |
+    |                      |                        |DNSSEC.                 |
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+
+OObbssoolleettee ooppppoorrttuunniissttiicc TTLLSS ccoonnffiigguurraattiioonn
+
+The postconf(1) command logs one of the following:
+
+  * support for parameter "lmtp_use_tls" will be removed; instead, specify
+    "lmtp_tls_security_level"
+  * support for parameter "smtp_use_tls" will be removed; instead, specify
+    "smtp_tls_security_level"
+  * support for parameter "smtpd_use_tls" will be removed; instead, specify
+    "smtpd_tls_security_level"
+
+There are similarly-named parameters and warnings for postscreen(8) and
+tlsproxy(8), but those parameters should rarely be specified by hand.
+
+Replace obsolete configuration with its replacement:
+
+     _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
+    |GGooaall                    |OObbssoolleettee ccoonnffiigguurraattiioonn|RReeppllaacceemmeenntt ccoonnffiigguurraattiioonn|
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+    |To turn off TLS         |xxx_use_tls = no      |xxx_security_level = none|
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+    |To turn on opportunistic|xxx_use_tls = yes     |xxx_security_level = may |
+    |TLS                     |                      |                         |
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+
+OObbssoolleettee mmaannddaattoorryy TTLLSS ccoonnffiigguurraattiioonn
+
+The postconf(1) command logs one of the following:
+
+  * support for parameter "lmtp_enforce_tls" will be removed; instead, specify
+    "lmtp_tls_security_level"
+  * support for parameter "smtp_enforce_tls" will be removed; instead, specify
+    "smtp_tls_security_level"
+  * support for parameter "smtpd_enforce_tls" will be removed; instead, specify
+    "smtpd_tls_security_level"
+
+There are similarly-named parameters and warnings for postscreen(8) and
+tlsproxy(8), but those parameters should rarely be specified by hand.
+
+Replace obsolete configuration with its replacement:
+
+     _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
+    |GGooaall                    |OObbssoolleettee ccoonnffiigguurraattiioonn|RReeppllaacceemmeenntt ccoonnffiigguurraattiioonn|
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+    |To turn off mandatory   |xxx_enforce_tls = no  |xxx_security_level = may |
+    |TLS                     |                      |                         |
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+    |To turn on mandatory TLS|xxx_enforce_tls = yes |xxx_security_level =     |
+    |                        |                      |encrypt                  |
+    |_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _|_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
+
+OObbssoolleettee TTLLSS ppoolliiccyy ttaabbllee ccoonnffiigguurraattiioonn
+
+The postconf(1) command logs one of the following:
+
+  * support for parameter "lmtp_tls_per_site" will be removed; instead, specify
+    "lmtp_tls_policy_maps"
+  * support for parameter "smtp_tls_per_site" will be removed; instead, specify
+    "smtp_tls_policy_maps"
+
+There is similarly-named parameter and warning for tlsproxy(8), but that
+parameter should rarely be specified by hand.
+
+Unfortunately, this is more than a name change: the table format has changed
+too, as has the table search process. There is no simple conversion of the
+obsolete form to its replacement.
+
+cchheecckk__rreellaayy__ddoommaaiinnss
+
+Depending on the Postfix version, the Postfix SMTP daemon logs following
+warning:
+
+  * support for restriction "check_relay_domains" has been removed in Postfix
+    3.9"; instead, specify "reject_unauth_destination"
+  * support for restriction "check_relay_domains" will be removed from Postfix;
+    use "reject_unauth_destination" instead
+
+This feature was removed because it would relay based on the client domain
+name, which is not robust.
+
+Recommended configuration to prevent an "open relay" problem with the SMTP
+service on port 25:
+
+    main.cf:
+        smtpd_recipient_restrictions =
+            permit_mynetworks,
+            permit_sasl_authenticated,
+            reject_unauth_destination
+            ...other restrictions...
+
+Or equivalent in smtpd_relay_restrictions.
+
+ppeerrmmiitt__mmxx__bbaacckkuupp
+
+The Postfix version 3.9 and later SMTP daemon logs the following warning:
+
+  * support for restriction "permit_mx_backup" will be removed from Postfix;
+    instead, specify "relay_domains"
+
+This feature will be removed because it is too difficult to configure recipient
+address validation, making Postfix a source of backscatter bounces.
+
+To specify the domains that Postfix will provide MX backup service for, see
+Configuring Postfix as primary or backup MX host for a remote site.
+
+rreejjeecctt__mmaappss__rrbbll
+
+Depending on the Postfix version, the SMTP daemon logs one of the following
+warnings:
+
+  * support for restriction "reject_maps_rbl" has been removed in Postfix 3.9";
+    instead, specify "reject_rbl_client domain-name"
+  * support for restriction "reject_maps_rbl" will be removed from Postfix; use
+    "reject_rbl_client domain-name" instead
+
+This feature was replaced because "MAPS RBL" is the name of a specific
+reputation service. The reject_rbl_client feature provides a superset of the
+reject_maps_rbl functionality.
+
+Recommended configuration:
+
+    main.cf:
+        smtpd_recipient_restrictions =
+            permit_mynetworks,
+            permit_sasl_authenticated,
+            reject_unauth_destination
+            reject_rbl_client domain-name
+            ...other restrictions...
+
+Where domain-name is the domain name of a DNS reputation service.
+
+ppeerrmmiitt__nnaakkeedd__iipp__aaddddrreessss
+
+Depending on the Postfix version, the SMTP daemon logs one of the following
+warnings:
+
+  * support for restriction "permit_naked_ip_address" has been removed in
+    Postfix 3.9"; instead, specify "permit_mynetworks" or
+    "permit_sasl_authenticated"
+  * restriction permit_naked_ip_address is deprecated. Use permit_mynetworks or
+    permit_sasl_authenticated instead
+
+This feature was removed because it was easy to get a false match when
+smtpd_recipient_restrictions was intended to match a remote SMTP client IP
+address.
+
+Recommended configuration:
+
+    main.cf:
+        smtpd_recipient_restrictions =
+            permit_mynetworks,
+            permit_sasl_authenticated,
+            reject_unauth_destination
+            reject_rbl_client domain-name
+            ...other restrictions...
+
+That is, no restriction on HELO or EHLO syntax. Such restrictions ar rarely
+useful nowadays.
+
diff --git a/postfix/conf/postfix-files b/postfix/conf/postfix-files
index bbc4dcd21..5a939822b 100644
--- a/postfix/conf/postfix-files
+++ b/postfix/conf/postfix-files
@@ -287,6 +287,7 @@ $readme_directory/CONTENT_INSPECTION_README:f:root:-:644
 $readme_directory/DATABASE_README:f:root:-:644
 $readme_directory/DB_README:f:root:-:644
 $readme_directory/DEBUG_README:f:root:-:644
+$readme_directory/DEPRECATION_README:f:root:-:644
 $readme_directory/DSN_README:f:root:-:644
 $readme_directory/ETRN_README:f:root:-:644
 $readme_directory/FILTER_README:f:root:-:644
@@ -351,6 +352,7 @@ $html_directory/CYRUS_README.html:f:root:-:644:o
 $html_directory/DATABASE_README.html:f:root:-:644
 $html_directory/DB_README.html:f:root:-:644
 $html_directory/DEBUG_README.html:f:root:-:644
+$html_directory/DEPRECATION_README.html:f:root:-:644
 $html_directory/DSN_README.html:f:root:-:644
 $html_directory/ETRN_README.html:f:root:-:644
 $html_directory/FILTER_README.html:f:root:-:644
diff --git a/postfix/html/DEPRECATION_README.html b/postfix/html/DEPRECATION_README.html
new file mode 100644
index 000000000..47295681e
--- /dev/null
+++ b/postfix/html/DEPRECATION_README.html
@@ -0,0 +1,411 @@
+<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN"
+       "http://www.w3.org/TR/html4/loose.dtd">
+
+<html>
+
+<head>
+
+<title>Postfix Replacements for Deprecated Features </title>
+
+<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
+<link rel='stylesheet' type='text/css' href='postfix-doc.css'>
+
+</head>
+
+<body>
+
+<h1><img src="postfix-logo.jpg" width="203" height="98" ALT="">Postfix
+Replacements for Deprecated Features</h1>
+
+<hr>
+
+<h2>Purpose of this document </h2>
+
+<p> This document describes Postfix features that are deprecated
+(will be removed) or that have already been removed. It also has
+tips for making an existing Postfix configuration more future-proof.
+</p>
+
+<p> Overview: </p>
+
+<ul>
+
+<li> <a href="#why"> Why deprecate? </a> 
+
+<li> <a href="#process"> Deprecation process </a> 
+
+<li> <a href="#features"> Deprecated features </a> 
+
+</ul>
+
+<h2> <a name="why"> Why deprecate? </a> </h2>
+
+<p> Sometimes, a Postfix feature needs to be replaced with a different
+one. To give an example: </p>
+
+<ul>
+
+<li> <p> The initial Postfix TLS implementation used multiple boolean
+parameters: one parameter to enable opportunistic TLS (for example, 
+"<a href="postconf.5.html#smtp_enforce_tls">smtp_enforce_tls</a> = yes") and one parameter to enable mandatory TLS
+(for example, "smtp_require_tls = yes"). </p>
+
+<li> <p> As we added support more features such as fingerprint,
+dane, and so on, we decided not to add more boolean parameters.
+Instead we introduced one configuration parameter to select from
+multiple deployment models (for example, <a href="postconf.5.html#smtp_tls_security_level">smtp_tls_security_level</a> =
+may | encrypt | dane, etc...). </p>
+
+</ul>
+
+<!--
+
+<p> Over time it has become clear that 'level' is too rigid, so this may
+have to change again. Wietse and Viktor have been discussing a way to
+specify a range with minimum properties that are required (e.g., encrypt)
+and nice-to-have properties if they are available (dane or mta-sts). </p>
+
+-->
+
+<p> Having both the "old" and "new" way to configure Postfix is
+convenient for existing Postfix installations, because their
+configuration does not break after an upgrade to a new version.
+Unfortunately, there are also disadvantages. Having multiple ways
+to do similar things is not only confusing for newcomers, it also
+makes Postfix harder to change. </p>
+
+<h2> <a name="process"> Deprecation process </a> </h2>
+
+<p> The basic process steps are: </p>
+
+<ol>
+
+<li> <p> Inform humans that a feature will be removed, and suggest
+replacements, in logging and documentation. </p>
+
+<li> <p> Remove the feature, and update logging and documentation.  </p>
+
+</ol>
+
+<p> Disclaimer: it has taken 20 years for some features to be
+removed. This past is not a guarantee for the future. </p>
+
+<h2> <a name="features"> Deprecated features </a> </h2>
+
+<p> The table summarizes removed or deprecated features and
+replacements. Click on the "obsolete feature" name for a more
+detailed description. </p>
+
+<blockquote>
+
+<table border="1">
+
+<tr> <th> Obsolete feature name </th> <th> Warning as <br> of version
+</th> <th> Removed <br> in version </th> <th> Replacement </th>
+</tr>
+
+<tr> <td> <a href="#disable_dns_lookups"> disable_dns_lookups </a>
+</td> <td align="center"> 3.9 </td> <td align="center"> - </td>
+<td> <a href="postconf.5.html#smtp_dns_support_level">smtp_dns_support_level</a> </td> </tr>
+
+<tr> <td> <a href="#xxx_enforce_tls"> <i>xxx</i>_use_tls </a> </td>
+<td align="center"> 3.9 </td> <td align="center"> - </td> <td>
+<i>xxx</i>_tls_security_level </td> </tr>
+
+<tr> <td> <a href="#xxx_enforce_tls"> <i>xxx</i>_enforce_tls </a>
+</td> <td align="center"> 3.9 </td> <td align="center"> - </td>
+<td> <i>xxx</i>_tls_security_level </td> </tr>
+
+<tr> <td> <a href="#xxx_per_site"> <i>xxx</i>_per_site </a> </td>
+<td align="center"> 3.9 </td> <td align="center"> - </td> <td>
+<i>xxx</i>_policy_maps </td> </tr>
+
+<tr> <td> <a href="#smtpd_tls_dh1024_param_file">
+smtpd_tls_dh1024_param_file </a> </td> <td align="center"> 3.9 </td>
+<td align="center"> - </td> <td> do not specify (leave at default)
+</td> </tr>
+
+<tr> <td> <a href="#smtpd_tls_eecdh_grade"> smtpd_tls_eecdh_grade
+</a> </td> <td align="center"> 3.9 </td> <td align="center"> - </td>
+<td> do not specify (leave at default) </td> </tr>
+
+<tr> <td> <a href="#permit_mx_backup"> permit_mx_backup </a> </td>
+<td align="center"> 3.9 </td> <td align="center"> - </td> <td>
+<a href="postconf.5.html#relay_domains">relay_domains</a> </td> </tr>
+
+<tr> <td> <a href="#check_relay_domains"> check_relay_domains </a>
+</td> <td align="center"> 2.2 </td> <td align="center"> 3.9 </td>
+<td> <a href="postconf.5.html#permit_mynetworks">permit_mynetworks</a>, <a href="postconf.5.html#reject_unauth_destination">reject_unauth_destination</a> </td> </tr>
+
+<tr> <td> <a href="#reject_maps_rbl"> reject_maps_rbl </a> </td>
+<td align="center"> 2.1 </td> <td align="center"> 3.9 </td> <td>
+<a href="postconf.5.html#reject_rbl_client">reject_rbl_client</a> </td> </tr>
+
+<tr> <td> <a href="#permit_naked_ip_address"> permit_naked_ip_address
+</a> </td> <td align="center"> 2.0 </td> <td align="center"> 3.9
+</td> <td> <a href="postconf.5.html#permit_mynetworks">permit_mynetworks</a>, <a href="postconf.5.html#permit_sasl_authenticated">permit_sasl_authenticated</a> </td> </tr>
+
+</table>
+
+</blockquote>
+
+<h3> <a name="disable_dns_lookups"> Obsolete DNS on/off configuration
+</a> </h3>
+
+<p> The <a href="postconf.1.html">postconf(1)</a> command logs the following: </p>
+
+<ul>
+
+<li> support for parameter "<a href="postconf.5.html#disable_dns_lookups">disable_dns_lookups</a>" will be removed; instead, specify "<a href="postconf.5.html#smtp_dns_support_level">smtp_dns_support_level</a>"
+
+</ul>
+
+<p> Replace obsolete configuration with its replacement: </p>
+
+<blockquote>
+
+<table border="1">
+
+<tr> <th width="33%"> Goal </th> <th width="33%"> Obsolete configuration
+</th> <th> Replacement configuration </th> </tr>
+
+<tr> <td> To disable DNS lookups in the Postfix SMTP/LMTP client
+</td> <td> <a href="postconf.5.html#disable_dns_lookups">disable_dns_lookups</a> = yes </td> <td> <a href="postconf.5.html#smtp_dns_support_level">smtp_dns_support_level</a>
+= disabled </td> </tr>
+
+<tr> <td> To enable DNS lookups in the Postfix SMTP/LMTP client </td> <td> 
+<a href="postconf.5.html#disable_dns_lookups">disable_dns_lookups</a> = no </td> <td> 
+Leave <a href="postconf.5.html#smtp_dns_support_level">smtp_dns_support_level</a> at the implicit default which is empty, unless
+you need a higher support level such as DNSSEC. </td> </tr>
+
+</table>
+
+</blockquote>
+
+<h3> <a name="xxx_use_tls"> Obsolete opportunistic TLS configuration
+</a> </h3>
+
+<p> The <a href="postconf.1.html">postconf(1)</a> command logs one of the following: </p>
+
+<ul>
+
+<li> support for parameter "<a href="postconf.5.html#lmtp_use_tls">lmtp_use_tls</a>" will be removed; instead, specify "<a href="postconf.5.html#lmtp_tls_security_level">lmtp_tls_security_level</a>"
+
+<li> support for parameter "<a href="postconf.5.html#smtp_use_tls">smtp_use_tls</a>" will be removed; instead, specify "<a href="postconf.5.html#smtp_tls_security_level">smtp_tls_security_level</a>"
+
+<li> support for parameter "<a href="postconf.5.html#smtpd_use_tls">smtpd_use_tls</a>" will be removed; instead, specify "<a href="postconf.5.html#smtpd_tls_security_level">smtpd_tls_security_level</a>"
+
+</ul>
+
+<p> There are similarly-named parameters and warnings for <a href="postscreen.8.html">postscreen(8)</a>
+and <a href="tlsproxy.8.html">tlsproxy(8)</a>, but those parameters should rarely be specified
+by hand. </p>
+
+<p> Replace obsolete configuration with its replacement: </p>
+
+<blockquote>
+
+<table border="1">
+
+<tr> <th width="33%"> Goal </th> <th width="33%"> Obsolete configuration </th> <th> Replacement configuration </th> </tr>
+
+<tr> <td> To turn off TLS </td> <td> <i>xxx</i>_use_tls = no </td>
+<td> <i>xxx</i>_security_level = none </td> </tr>
+
+<tr> <td> To turn on opportunistic TLS </td> <td> <i>xxx</i>_use_tls
+= yes </td> <td> <i>xxx</i>_security_level = may </td> </tr>
+
+</table>
+
+</blockquote>
+
+<h3> <a name="xxx_enforce_tls"> Obsolete mandatory TLS configuration
+</a> </h3>
+
+<p> The <a href="postconf.1.html">postconf(1)</a> command logs one of the following: </p>
+
+<ul>
+
+<li> support for parameter "<a href="postconf.5.html#lmtp_enforce_tls">lmtp_enforce_tls</a>" will be removed; instead, specify "<a href="postconf.5.html#lmtp_tls_security_level">lmtp_tls_security_level</a>"
+
+<li> support for parameter "<a href="postconf.5.html#smtp_enforce_tls">smtp_enforce_tls</a>" will be removed; instead, specify "<a href="postconf.5.html#smtp_tls_security_level">smtp_tls_security_level</a>"
+
+<li> support for parameter "<a href="postconf.5.html#smtpd_enforce_tls">smtpd_enforce_tls</a>" will be removed; instead, specify "<a href="postconf.5.html#smtpd_tls_security_level">smtpd_tls_security_level</a>"
+
+</ul>
+
+<p> There are similarly-named parameters and warnings for <a href="postscreen.8.html">postscreen(8)</a>
+and <a href="tlsproxy.8.html">tlsproxy(8)</a>, but those parameters should rarely be specified
+by hand. </p>
+
+<p> Replace obsolete configuration with its replacement: </p>
+
+<blockquote>
+
+<table border="1">
+
+<tr> <th width="33%"> Goal </th> <th width="33%"> Obsolete configuration </th> <th> Replacement configuration </th> </tr>
+
+<tr> <td> To turn off mandatory TLS </td> <td> <i>xxx</i>_enforce_tls
+= no </td> <td> <i>xxx</i>_security_level = may </td> </tr>
+
+<tr> <td> To turn on mandatory TLS </td> <td> <i>xxx</i>_enforce_tls
+= yes </td> <td> <i>xxx</i>_security_level = encrypt </td> </tr>
+
+</table>
+
+</blockquote>
+
+<h3> <a name="xxx_per_site"> Obsolete TLS policy table configuration
+</a> </h3>
+
+<p> The <a href="postconf.1.html">postconf(1)</a> command logs one of the following: </p>
+
+<ul>
+
+<li> support for parameter "<a href="postconf.5.html#lmtp_tls_per_site">lmtp_tls_per_site</a>" will be removed;
+instead, specify "<a href="postconf.5.html#lmtp_tls_policy_maps">lmtp_tls_policy_maps</a>"
+
+<li> support for parameter "<a href="postconf.5.html#smtp_tls_per_site">smtp_tls_per_site</a>" will be removed;
+instead, specify "<a href="postconf.5.html#smtp_tls_policy_maps">smtp_tls_policy_maps</a>"
+
+</ul>
+
+<p> There is similarly-named parameter and warning for <a href="tlsproxy.8.html">tlsproxy(8)</a>,
+but that parameter should rarely be specified by hand. </p>
+
+<p> Unfortunately, this is more than a name change: the table format
+has changed too, as has the table search process. There is no simple
+conversion of the obsolete form to its replacement. </p>
+
+<h3> <a name="check_relay_domains"> check_relay_domains </a> </h3>
+
+<p> Depending on the Postfix version, the Postfix SMTP daemon logs
+following warning: </p>
+
+<ul>
+
+<li> support for restriction "check_relay_domains" has been removed
+in Postfix 3.9"; instead, specify "<a href="postconf.5.html#reject_unauth_destination">reject_unauth_destination</a>"
+
+<li> support for restriction "check_relay_domains" will be removed
+from Postfix; use "<a href="postconf.5.html#reject_unauth_destination">reject_unauth_destination</a>" instead
+
+</ul>
+
+<p> This feature was removed because it would relay based on the
+client domain name, which is not robust. </p>
+
+<p> Recommended configuration to prevent an "open relay" problem
+with the SMTP service on port 25:
+</p>
+
+<blockquote>
+<pre>
+<a href="postconf.5.html">main.cf</a>:
+    <a href="postconf.5.html#smtpd_recipient_restrictions">smtpd_recipient_restrictions</a> = 
+        <a href="postconf.5.html#permit_mynetworks">permit_mynetworks</a>, 
+        <a href="postconf.5.html#permit_sasl_authenticated">permit_sasl_authenticated</a>, 
+        <a href="postconf.5.html#reject_unauth_destination">reject_unauth_destination</a>
+        ...other restrictions...
+</pre>
+</blockquote>
+
+<p> Or equivalent in <a href="postconf.5.html#smtpd_relay_restrictions">smtpd_relay_restrictions</a>. </p>
+
+<h3> <a name="permit_mx_backup"> permit_mx_backup</a> </h3>
+
+<p> The Postfix version 3.9 and later SMTP daemon logs the following
+warning: </p>
+
+<ul>
+
+<li> support for restriction "<a href="postconf.5.html#permit_mx_backup">permit_mx_backup</a>" will be removed
+from Postfix; instead, specify "<a href="postconf.5.html#relay_domains">relay_domains</a>"
+
+</ul>
+
+<p> This feature will be removed because it is too difficult to
+configure recipient address validation, making Postfix a source of
+backscatter bounces. </p>
+
+<p> To specify the domains that Postfix will provide MX backup
+service for, see <a href="STANDARD_CONFIGURATION_README.html#backup">
+Configuring Postfix as primary or backup MX host for a remote
+site</a>. </p>
+
+<h3> <a name="reject_maps_rbl"> reject_maps_rbl</a> </h3>
+
+<p> Depending on the Postfix version, the SMTP daemon logs one of
+the following warnings: </p>
+
+<ul>
+
+<li> support for restriction "reject_maps_rbl" has been removed in
+Postfix 3.9"; instead, specify "<a href="postconf.5.html#reject_rbl_client">reject_rbl_client</a> domain-name"
+
+<li> support for restriction "reject_maps_rbl" will be removed from
+Postfix; use "<a href="postconf.5.html#reject_rbl_client">reject_rbl_client</a> domain-name" instead
+
+</ul>
+
+<p> This feature was replaced because "MAPS RBL" is the name of a
+specific reputation service. The <a href="postconf.5.html#reject_rbl_client">reject_rbl_client</a> feature provides
+a superset of the reject_maps_rbl functionality. </p>
+
+<p> Recommended configuration: </p>
+
+<blockquote>
+<pre>
+<a href="postconf.5.html">main.cf</a>:
+    <a href="postconf.5.html#smtpd_recipient_restrictions">smtpd_recipient_restrictions</a> =
+        <a href="postconf.5.html#permit_mynetworks">permit_mynetworks</a>,
+        <a href="postconf.5.html#permit_sasl_authenticated">permit_sasl_authenticated</a>,
+        <a href="postconf.5.html#reject_unauth_destination">reject_unauth_destination</a>
+        <a href="postconf.5.html#reject_rbl_client">reject_rbl_client</a> <i>domain-name</i>
+        ...other restrictions...
+</pre>
+</blockquote>
+
+<p> Where <i>domain-name</i> is the domain name of a DNS reputation service. </p>
+
+<h3> <a name="permit_naked_ip_address"> permit_naked_ip_address</a> </h3>
+
+<p> Depending on the Postfix version, the SMTP daemon logs one of
+the following warnings: </p>
+
+<ul>
+
+<li> support for restriction "permit_naked_ip_address" has been
+removed in Postfix 3.9"; instead, specify "<a href="postconf.5.html#permit_mynetworks">permit_mynetworks</a>" or
+"<a href="postconf.5.html#permit_sasl_authenticated">permit_sasl_authenticated</a>"
+
+<li> restriction permit_naked_ip_address is deprecated. Use
+<a href="postconf.5.html#permit_mynetworks">permit_mynetworks</a> or <a href="postconf.5.html#permit_sasl_authenticated">permit_sasl_authenticated</a> instead
+
+</ul>
+
+<p> This feature was removed because it was easy to get a false
+match when <a href="postconf.5.html#smtpd_recipient_restrictions">smtpd_recipient_restrictions</a> was intended to match a
+remote SMTP client IP address. </p>
+
+<p> Recommended configuration: </p>
+
+<blockquote>
+<pre>
+<a href="postconf.5.html">main.cf</a>:
+    <a href="postconf.5.html#smtpd_recipient_restrictions">smtpd_recipient_restrictions</a> =
+        <a href="postconf.5.html#permit_mynetworks">permit_mynetworks</a>,
+        <a href="postconf.5.html#permit_sasl_authenticated">permit_sasl_authenticated</a>,
+        <a href="postconf.5.html#reject_unauth_destination">reject_unauth_destination</a>
+        <a href="postconf.5.html#reject_rbl_client">reject_rbl_client</a> <i>domain-name</i>
+        ...other restrictions...
+</pre>
+</blockquote>
+
+<p> That is, no restriction on HELO or EHLO syntax. Such restrictions
+ar rarely useful nowadays.
+
+</body>
+
+</html>
diff --git a/postfix/html/index.html b/postfix/html/index.html
index fe1bfab98..a7da6cb51 100644
--- a/postfix/html/index.html
+++ b/postfix/html/index.html
@@ -53,6 +53,8 @@ configuration examples </a>
 
 <li> <a href="COMPATIBILITY_README.html"> Backwards-Compatibility Safety Net</a>
 
+<li> <a href="DEPRECATION_README.html"> Deprecated features and alternatives </a>
+
 <li> <a href="INSTALL.html"> Installation from source code </a>
 
 </ul>
diff --git a/postfix/html/master.5.html b/postfix/html/master.5.html
index 04a0c427c..b2d3e70b5 100644
--- a/postfix/html/master.5.html
+++ b/postfix/html/master.5.html
@@ -227,9 +227,11 @@ MASTER(5)                                                            MASTER(5)
                      verbose.
 
               Other command-line arguments
-                     Specify "{" and "}" around command arguments that contain
-                     whitespace (Postfix 3.0 and later). Whitespace after  "{"
-                     and before "}" is ignored.
+                     Specify  "{"  and  "}" around command arguments that must
+                     start with "{" or that must contain  whitespace  (Postfix
+                     3.0  and  later).  The outer "{" and "}" are removed from
+                     the input, together with any leading or  trailing  white-
+                     space.
 
 <b>SEE ALSO</b>
        <a href="master.8.html">master(8)</a>, process manager
diff --git a/postfix/man/man5/master.5 b/postfix/man/man5/master.5
index 48fd4fd45..4b2573cc2 100644
--- a/postfix/man/man5/master.5
+++ b/postfix/man/man5/master.5
@@ -226,9 +226,10 @@ personalities via master.cf.
 Increase the verbose logging level. Specify multiple \fB\-v\fR
 options to make a Postfix daemon process increasingly verbose.
 .IP "Other command\-line arguments"
-Specify "{" and "}" around command arguments that contain
-whitespace (Postfix 3.0 and later). Whitespace
-after "{" and before "}" is ignored.
+Specify "{" and "}" around command arguments that must start
+with "{" or that must contain whitespace (Postfix 3.0 and
+later). The outer "{" and "}" are removed from the input,
+together with any leading or trailing whitespace.
 .SH "SEE ALSO"
 .na
 .nf
diff --git a/postfix/proto/DEPRECATION_README.html b/postfix/proto/DEPRECATION_README.html
new file mode 100644
index 000000000..1ded55505
--- /dev/null
+++ b/postfix/proto/DEPRECATION_README.html
@@ -0,0 +1,411 @@
+<!doctype html public "-//W3C//DTD HTML 4.01 Transitional//EN"
+       "http://www.w3.org/TR/html4/loose.dtd">
+
+<html>
+
+<head>
+
+<title>Postfix Replacements for Deprecated Features </title>
+
+<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
+<link rel='stylesheet' type='text/css' href='postfix-doc.css'>
+
+</head>
+
+<body>
+
+<h1><img src="postfix-logo.jpg" width="203" height="98" ALT="">Postfix
+Replacements for Deprecated Features</h1>
+
+<hr>
+
+<h2>Purpose of this document </h2>
+
+<p> This document describes Postfix features that are deprecated
+(will be removed) or that have already been removed. It also has
+tips for making an existing Postfix configuration more future-proof.
+</p>
+
+<p> Overview: </p>
+
+<ul>
+
+<li> <a href="#why"> Why deprecate? </a> 
+
+<li> <a href="#process"> Deprecation process </a> 
+
+<li> <a href="#features"> Deprecated features </a> 
+
+</ul>
+
+<h2> <a name="why"> Why deprecate? </a> </h2>
+
+<p> Sometimes, a Postfix feature needs to be replaced with a different
+one. To give an example: </p>
+
+<ul>
+
+<li> <p> The initial Postfix TLS implementation used multiple boolean
+parameters: one parameter to enable opportunistic TLS (for example, 
+"smtp_enforce_tls = yes") and one parameter to enable mandatory TLS
+(for example, "smtp_require_tls = yes"). </p>
+
+<li> <p> As we added support more features such as fingerprint,
+dane, and so on, we decided not to add more boolean parameters.
+Instead we introduced one configuration parameter to select from
+multiple deployment models (for example, smtp_tls_security_level =
+may | encrypt | dane, etc...). </p>
+
+</ul>
+
+<!--
+
+<p> Over time it has become clear that 'level' is too rigid, so this may
+have to change again. Wietse and Viktor have been discussing a way to
+specify a range with minimum properties that are required (e.g., encrypt)
+and nice-to-have properties if they are available (dane or mta-sts). </p>
+
+-->
+
+<p> Having both the "old" and "new" way to configure Postfix is
+convenient for existing Postfix installations, because their
+configuration does not break after an upgrade to a new version.
+Unfortunately, there are also disadvantages. Having multiple ways
+to do similar things is not only confusing for newcomers, it also
+makes Postfix harder to change. </p>
+
+<h2> <a name="process"> Deprecation process </a> </h2>
+
+<p> The basic process steps are: </p>
+
+<ol>
+
+<li> <p> Inform humans that a feature will be removed, and suggest
+replacements, in logging and documentation. </p>
+
+<li> <p> Remove the feature, and update logging and documentation.  </p>
+
+</ol>
+
+<p> Disclaimer: it has taken 20 years for some features to be
+removed. This past is not a guarantee for the future. </p>
+
+<h2> <a name="features"> Deprecated features </a> </h2>
+
+<p> The table summarizes removed or deprecated features and
+replacements. Click on the "obsolete feature" name for a more
+detailed description. </p>
+
+<blockquote>
+
+<table border="1">
+
+<tr> <th> Obsolete feature name </th> <th> Warning as <br> of version
+</th> <th> Removed <br> in version </th> <th> Replacement </th>
+</tr>
+
+<tr> <td> <a href="#disable_dns_lookups"> disable_dns_lookups </a>
+</td> <td align="center"> 3.9 </td> <td align="center"> - </td>
+<td> smtp_dns_support_level </td> </tr>
+
+<tr> <td> <a href="#xxx_enforce_tls"> <i>xxx</i>_use_tls </a> </td>
+<td align="center"> 3.9 </td> <td align="center"> - </td> <td>
+<i>xxx</i>_tls_security_level </td> </tr>
+
+<tr> <td> <a href="#xxx_enforce_tls"> <i>xxx</i>_enforce_tls </a>
+</td> <td align="center"> 3.9 </td> <td align="center"> - </td>
+<td> <i>xxx</i>_tls_security_level </td> </tr>
+
+<tr> <td> <a href="#xxx_per_site"> <i>xxx</i>_per_site </a> </td>
+<td align="center"> 3.9 </td> <td align="center"> - </td> <td>
+<i>xxx</i>_policy_maps </td> </tr>
+
+<tr> <td> <a href="#smtpd_tls_dh1024_param_file">
+smtpd_tls_dh1024_param_file </a> </td> <td align="center"> 3.9 </td>
+<td align="center"> - </td> <td> do not specify (leave at default)
+</td> </tr>
+
+<tr> <td> <a href="#smtpd_tls_eecdh_grade"> smtpd_tls_eecdh_grade
+</a> </td> <td align="center"> 3.9 </td> <td align="center"> - </td>
+<td> do not specify (leave at default) </td> </tr>
+
+<tr> <td> <a href="#permit_mx_backup"> permit_mx_backup </a> </td>
+<td align="center"> 3.9 </td> <td align="center"> - </td> <td>
+relay_domains </td> </tr>
+
+<tr> <td> <a href="#check_relay_domains"> check_relay_domains </a>
+</td> <td align="center"> 2.2 </td> <td align="center"> 3.9 </td>
+<td> permit_mynetworks, reject_unauth_destination </td> </tr>
+
+<tr> <td> <a href="#reject_maps_rbl"> reject_maps_rbl </a> </td>
+<td align="center"> 2.1 </td> <td align="center"> 3.9 </td> <td>
+reject_rbl_client </td> </tr>
+
+<tr> <td> <a href="#permit_naked_ip_address"> permit_naked_ip_address
+</a> </td> <td align="center"> 2.0 </td> <td align="center"> 3.9
+</td> <td> permit_mynetworks, permit_sasl_authenticated </td> </tr>
+
+</table>
+
+</blockquote>
+
+<h3> <a name="disable_dns_lookups"> Obsolete DNS on/off configuration
+</a> </h3>
+
+<p> The postconf(1) command logs the following: </p>
+
+<ul>
+
+<li> support for parameter "disable_dns_lookups" will be removed; instead, specify "smtp_dns_support_level"
+
+</ul>
+
+<p> Replace obsolete configuration with its replacement: </p>
+
+<blockquote>
+
+<table border="1">
+
+<tr> <th width="33%"> Goal </th> <th width="33%"> Obsolete configuration
+</th> <th> Replacement configuration </th> </tr>
+
+<tr> <td> To disable DNS lookups in the Postfix SMTP/LMTP client
+</td> <td> disable_dns_lookups = yes </td> <td> smtp_dns_support_level
+= disabled </td> </tr>
+
+<tr> <td> To enable DNS lookups in the Postfix SMTP/LMTP client </td> <td> 
+disable_dns_lookups = no </td> <td> 
+Leave smtp_dns_support_level at the implicit default which is empty, unless
+you need a higher support level such as DNSSEC. </td> </tr>
+
+</table>
+
+</blockquote>
+
+<h3> <a name="xxx_use_tls"> Obsolete opportunistic TLS configuration
+</a> </h3>
+
+<p> The postconf(1) command logs one of the following: </p>
+
+<ul>
+
+<li> support for parameter "lmtp_use_tls" will be removed; instead, specify "lmtp_tls_security_level"
+
+<li> support for parameter "smtp_use_tls" will be removed; instead, specify "smtp_tls_security_level"
+
+<li> support for parameter "smtpd_use_tls" will be removed; instead, specify "smtpd_tls_security_level"
+
+</ul>
+
+<p> There are similarly-named parameters and warnings for postscreen(8)
+and tlsproxy(8), but those parameters should rarely be specified
+by hand. </p>
+
+<p> Replace obsolete configuration with its replacement: </p>
+
+<blockquote>
+
+<table border="1">
+
+<tr> <th width="33%"> Goal </th> <th width="33%"> Obsolete configuration </th> <th> Replacement configuration </th> </tr>
+
+<tr> <td> To turn off TLS </td> <td> <i>xxx</i>_use_tls = no </td>
+<td> <i>xxx</i>_security_level = none </td> </tr>
+
+<tr> <td> To turn on opportunistic TLS </td> <td> <i>xxx</i>_use_tls
+= yes </td> <td> <i>xxx</i>_security_level = may </td> </tr>
+
+</table>
+
+</blockquote>
+
+<h3> <a name="xxx_enforce_tls"> Obsolete mandatory TLS configuration
+</a> </h3>
+
+<p> The postconf(1) command logs one of the following: </p>
+
+<ul>
+
+<li> support for parameter "lmtp_enforce_tls" will be removed; instead, specify "lmtp_tls_security_level"
+
+<li> support for parameter "smtp_enforce_tls" will be removed; instead, specify "smtp_tls_security_level"
+
+<li> support for parameter "smtpd_enforce_tls" will be removed; instead, specify "smtpd_tls_security_level"
+
+</ul>
+
+<p> There are similarly-named parameters and warnings for postscreen(8)
+and tlsproxy(8), but those parameters should rarely be specified
+by hand. </p>
+
+<p> Replace obsolete configuration with its replacement: </p>
+
+<blockquote>
+
+<table border="1">
+
+<tr> <th width="33%"> Goal </th> <th width="33%"> Obsolete configuration </th> <th> Replacement configuration </th> </tr>
+
+<tr> <td> To turn off mandatory TLS </td> <td> <i>xxx</i>_enforce_tls
+= no </td> <td> <i>xxx</i>_security_level = may </td> </tr>
+
+<tr> <td> To turn on mandatory TLS </td> <td> <i>xxx</i>_enforce_tls
+= yes </td> <td> <i>xxx</i>_security_level = encrypt </td> </tr>
+
+</table>
+
+</blockquote>
+
+<h3> <a name="xxx_per_site"> Obsolete TLS policy table configuration
+</a> </h3>
+
+<p> The postconf(1) command logs one of the following: </p>
+
+<ul>
+
+<li> support for parameter "lmtp_tls_per_site" will be removed;
+instead, specify "lmtp_tls_policy_maps"
+
+<li> support for parameter "smtp_tls_per_site" will be removed;
+instead, specify "smtp_tls_policy_maps"
+
+</ul>
+
+<p> There is similarly-named parameter and warning for tlsproxy(8),
+but that parameter should rarely be specified by hand. </p>
+
+<p> Unfortunately, this is more than a name change: the table format
+has changed too, as has the table search process. There is no simple
+conversion of the obsolete form to its replacement. </p>
+
+<h3> <a name="check_relay_domains"> check_relay_domains </a> </h3>
+
+<p> Depending on the Postfix version, the Postfix SMTP daemon logs
+following warning: </p>
+
+<ul>
+
+<li> support for restriction "check_relay_domains" has been removed
+in Postfix 3.9"; instead, specify "reject_unauth_destination"
+
+<li> support for restriction "check_relay_domains" will be removed
+from Postfix; use "reject_unauth_destination" instead
+
+</ul>
+
+<p> This feature was removed because it would relay based on the
+client domain name, which is not robust. </p>
+
+<p> Recommended configuration to prevent an "open relay" problem
+with the SMTP service on port 25:
+</p>
+
+<blockquote>
+<pre>
+main.cf:
+    smtpd_recipient_restrictions = 
+	permit_mynetworks, 
+	permit_sasl_authenticated, 
+	reject_unauth_destination
+	...other restrictions...
+</pre>
+</blockquote>
+
+<p> Or equivalent in smtpd_relay_restrictions. </p>
+
+<h3> <a name="permit_mx_backup"> permit_mx_backup</a> </h3>
+
+<p> The Postfix version 3.9 and later SMTP daemon logs the following
+warning: </p>
+
+<ul>
+
+<li> support for restriction "permit_mx_backup" will be removed
+from Postfix; instead, specify "relay_domains"
+
+</ul>
+
+<p> This feature will be removed because it is too difficult to
+configure recipient address validation, making Postfix a source of
+backscatter bounces. </p>
+
+<p> To specify the domains that Postfix will provide MX backup
+service for, see <a href="STANDARD_CONFIGURATION_README.html#backup">
+Configuring Postfix as primary or backup MX host for a remote
+site</a>. </p>
+
+<h3> <a name="reject_maps_rbl"> reject_maps_rbl</a> </h3>
+
+<p> Depending on the Postfix version, the SMTP daemon logs one of
+the following warnings: </p>
+
+<ul>
+
+<li> support for restriction "reject_maps_rbl" has been removed in
+Postfix 3.9"; instead, specify "reject_rbl_client domain-name"
+
+<li> support for restriction "reject_maps_rbl" will be removed from
+Postfix; use "reject_rbl_client domain-name" instead
+
+</ul>
+
+<p> This feature was replaced because "MAPS RBL" is the name of a
+specific reputation service. The reject_rbl_client feature provides
+a superset of the reject_maps_rbl functionality. </p>
+
+<p> Recommended configuration: </p>
+
+<blockquote>
+<pre>
+main.cf:
+    smtpd_recipient_restrictions =
+        permit_mynetworks,
+        permit_sasl_authenticated,
+        reject_unauth_destination
+	reject_rbl_client <i>domain-name</i>
+	...other restrictions...
+</pre>
+</blockquote>
+
+<p> Where <i>domain-name</i> is the domain name of a DNS reputation service. </p>
+
+<h3> <a name="permit_naked_ip_address"> permit_naked_ip_address</a> </h3>
+
+<p> Depending on the Postfix version, the SMTP daemon logs one of
+the following warnings: </p>
+
+<ul>
+
+<li> support for restriction "permit_naked_ip_address" has been
+removed in Postfix 3.9"; instead, specify "permit_mynetworks" or
+"permit_sasl_authenticated"
+
+<li> restriction permit_naked_ip_address is deprecated. Use
+permit_mynetworks or permit_sasl_authenticated instead
+
+</ul>
+
+<p> This feature was removed because it was easy to get a false
+match when smtpd_recipient_restrictions was intended to match a
+remote SMTP client IP address. </p>
+
+<p> Recommended configuration: </p>
+
+<blockquote>
+<pre>
+main.cf:
+    smtpd_recipient_restrictions =
+        permit_mynetworks,
+        permit_sasl_authenticated,
+        reject_unauth_destination
+        reject_rbl_client <i>domain-name</i>
+        ...other restrictions...
+</pre>
+</blockquote>
+
+<p> That is, no restriction on HELO or EHLO syntax. Such restrictions
+ar rarely useful nowadays.
+
+</body>
+
+</html>
diff --git a/postfix/proto/Makefile.in b/postfix/proto/Makefile.in
index ad7f73e50..f02ab1415 100644
--- a/postfix/proto/Makefile.in
+++ b/postfix/proto/Makefile.in
@@ -19,6 +19,7 @@ HTML	= ../html/ADDRESS_CLASS_README.html \
 	../html/CONTENT_INSPECTION_README.html \
 	../html/DATABASE_README.html ../html/DB_README.html \
 	../html/DEBUG_README.html \
+	../html/DEPRECATION_README.html \
 	../html/DSN_README.html \
 	../html/ETRN_README.html ../html/FILTER_README.html \
 	../html/FORWARD_SECRECY_README.html \
@@ -69,6 +70,7 @@ README	= ../README_FILES/ADDRESS_CLASS_README \
 	../README_FILES/DATABASE_README ../README_FILES/DB_README \
 	../README_FILES/DEBUG_README \
 	../README_FILES/DSN_README \
+	../README_FILES/DEPRECATION_README \
 	../README_FILES/ETRN_README ../README_FILES/FILTER_README \
 	../README_FILES/FORWARD_SECRECY_README \
 	../README_FILES/INSTALL ../README_FILES/IPV6_README \
@@ -200,6 +202,9 @@ clobber:
 ../html/DEBUG_README.html: DEBUG_README.html
 	$(DETAB) $? | $(POSTLINK) >$@
 
+../html/DEPRECATION_README.html: DEPRECATION_README.html
+	$(DETAB) $? | $(POSTLINK) >$@
+
 ../html/DSN_README.html: DSN_README.html
 	$(DETAB) $? | $(POSTLINK) >$@
 
@@ -386,6 +391,9 @@ clobber:
 ../README_FILES/DSN_README: DSN_README.html
 	$(DETAB) $? | $(HT2READ) >$@
 
+../README_FILES/DEPRECATION_README: DEPRECATION_README.html
+	$(DETAB) $? | $(HT2READ) >$@
+
 ../README_FILES/ETRN_README: ETRN_README.html
 	$(DETAB) $? | $(HT2READ) >$@
 
diff --git a/postfix/proto/master b/postfix/proto/master
index 28040b69a..693e9a4ff 100644
--- a/postfix/proto/master
+++ b/postfix/proto/master
@@ -220,9 +220,10 @@
 #	Increase the verbose logging level. Specify multiple \fB-v\fR
 #	options to make a Postfix daemon process increasingly verbose.
 # .IP "Other command-line arguments"
-#	Specify "{" and "}" around command arguments that contain
-#	whitespace (Postfix 3.0 and later). Whitespace
-#	after "{" and before "}" is ignored.
+#	Specify "{" and "}" around command arguments that must start
+#	with "{" or that must contain whitespace (Postfix 3.0 and
+#	later). The outer "{" and "}" are removed from the input,
+#	together with any leading or trailing whitespace.
 # SEE ALSO
 #	master(8), process manager
 #	postconf(5), configuration parameters
diff --git a/postfix/src/global/mail_version.h b/postfix/src/global/mail_version.h
index 3095c8a94..d4f945ea6 100644
--- a/postfix/src/global/mail_version.h
+++ b/postfix/src/global/mail_version.h
@@ -20,7 +20,7 @@
   * Patches change both the patchlevel and the release date. Snapshots have no
   * patchlevel; they change the release date only.
   */
-#define MAIL_RELEASE_DATE	"20240229"
+#define MAIL_RELEASE_DATE	"20240305"
 #define MAIL_VERSION_NUMBER	"3.9"
 
 #ifdef SNAPSHOT
diff --git a/postfix/src/postconf/postconf_unused.c b/postfix/src/postconf/postconf_unused.c
index a7e4febf7..717d1a53a 100644
--- a/postfix/src/postconf/postconf_unused.c
+++ b/postfix/src/postconf/postconf_unused.c
@@ -75,22 +75,22 @@ static const PCF_DEPR_PARAM_INFO pcf_depr_param_info[] = {
      * disable_dns_lookups parameter was documented as deprecated since
      * Postfix 2.11 but nothing was logged.
      */
-    "disable_dns_lookups", "specify smtp_dns_support_level",
-    "lmtp_use_tls", "specify lmtp_tls_security_level",
-    "postscreen_use_tls", "specify postscreen_tls_security_level",
-    "smtp_use_tls", "specify smtp_tls_security_level",
-    "smtpd_use_tls", "specify smtpd_tls_security_level",
-    "tlsproxy_client_use_tls", "specify tlsproxy_client_security_level",
-    "tlsproxy_use_tls", "specify tlsproxy_tls_security_level",
+    "disable_dns_lookups", "specify \"smtp_dns_support_level\"",
+    "lmtp_use_tls", "specify \"lmtp_tls_security_level\"",
+    "postscreen_use_tls", "specify \"postscreen_tls_security_level\"",
+    "smtp_use_tls", "specify \"smtp_tls_security_level\"",
+    "smtpd_use_tls", "specify \"smtpd_tls_security_level\"",
+    "tlsproxy_client_use_tls", "specify \"tlsproxy_client_security_level\"",
+    "tlsproxy_use_tls", "specify \"tlsproxy_tls_security_level\"",
     "lmtp_enforce_tls", "lmtp_tls_security_level",
-    "postscreen_enforce_tls", "specify postscreen_tls_security_level",
-    "smtp_enforce_tls", "specify smtp_tls_security_level",
-    "smtpd_enforce_tls", "specify smtpd_tls_security_level",
-    "tlsproxy_client_enforce_tls", "specify tlsproxy_client_security_level",
-    "tlsproxy_enforce_tls", "specify tlsproxy_tls_security_level",
-    "lmtp_tls_per_site", "specify lmtp_tls_policy_maps",
-    "smtp_tls_per_site", "specify smtp_tls_policy_maps",
-    "tlsproxy_client_per_site", "specify tlsproxy_client_policy_maps",
+    "postscreen_enforce_tls", "specify \"postscreen_tls_security_level\"",
+    "smtp_enforce_tls", "specify \"smtp_tls_security_level\"",
+    "smtpd_enforce_tls", "specify \"smtpd_tls_security_level\"",
+    "tlsproxy_client_enforce_tls", "specify \"tlsproxy_client_security_level\"",
+    "tlsproxy_enforce_tls", "specify \"tlsproxy_tls_security_level\"",
+    "lmtp_tls_per_site", "specify \"lmtp_tls_policy_maps\"",
+    "smtp_tls_per_site", "specify \"smtp_tls_policy_maps\"",
+    "tlsproxy_client_per_site", "specify \"tlsproxy_client_policy_maps\"",
     "smtpd_tls_dh1024_param_file", "do not specify (leave at default)",
     "smtpd_tls_eecdh_grade", "do not specify (leave at default)",
     "deleted-test-only", "do not specify",	/* For testing */
@@ -171,7 +171,7 @@ static void pcf_flag_unused_parameters(DICT *dict, const char *conf_name,
 	else if ((dp = (const PCF_DEPR_PARAM_INFO *)
 		  htable_find(pcf_depr_param_table, param_name)) != 0) {
 	    vstream_fflush(VSTREAM_OUT);
-	    msg_warn("%s/%s: support for parameter %s will be removed;"
+	    msg_warn("%s/%s: support for parameter \"%s\" will be removed;"
 		     " instead, %s", var_config_dir, conf_name,
 		     param_name, dp->alternative);
 	}
diff --git a/postfix/src/postconf/test76.ref b/postfix/src/postconf/test76.ref
index 29297ff62..3e4cd2640 100644
--- a/postfix/src/postconf/test76.ref
+++ b/postfix/src/postconf/test76.ref
@@ -2,8 +2,8 @@ config_directory = .
 disable_dns_lookups = no
 lmtp_use_tls = no
 smtpd_tls_dh1024_param_file = auto
-./postconf: warning: ./main.cf: support for parameter disable_dns_lookups will be removed; instead, specify smtp_dns_support_level
-./postconf: warning: ./main.cf: support for parameter lmtp_use_tls will be removed; instead, specify lmtp_tls_security_level
-./postconf: warning: ./main.cf: support for parameter smtpd_tls_dh1024_param_file will be removed; instead, do not specify (leave at default)
+./postconf: warning: ./main.cf: support for parameter "disable_dns_lookups" will be removed; instead, specify "smtp_dns_support_level"
+./postconf: warning: ./main.cf: support for parameter "lmtp_use_tls" will be removed; instead, specify "lmtp_tls_security_level"
+./postconf: warning: ./main.cf: support for parameter "smtpd_tls_dh1024_param_file" will be removed; instead, do not specify (leave at default)
 ./postconf: warning: ./main.cf: support for parameter deleted-test-only has been removed; instead, do not specify
-./postconf: warning: ./master.cf: support for parameter smtp_enforce_tls will be removed; instead, specify smtp_tls_security_level
+./postconf: warning: ./master.cf: support for parameter "smtp_enforce_tls" will be removed; instead, specify "smtp_tls_security_level"
diff --git a/postfix/src/smtpd/smtpd_check.c b/postfix/src/smtpd/smtpd_check.c
index 1ea31e7c6..6aeda7475 100644
--- a/postfix/src/smtpd/smtpd_check.c
+++ b/postfix/src/smtpd/smtpd_check.c
@@ -1679,7 +1679,7 @@ static int check_relay_domains(SMTPD_STATE *state, char *recipient,
 	msg_info("%s: %s", myname, recipient);
 
     msg_warn("support for restriction \"%s\" has been removed in %s 3.9; "
-	     "use \"%s\" instead",
+	     "instead, specify \"%s\"",
 	     CHECK_RELAY_DOMAINS, var_mail_name, REJECT_UNAUTH_DEST);
     reject_server_error(state);
 }
@@ -1998,7 +1998,7 @@ static int permit_mx_backup(SMTPD_STATE *state, const char *recipient,
     if (once == 0) {
 	once = 1;
 	msg_warn("support for restriction \"%s\" will be removed from %s; "
-		 "instead, use \"%s\"",
+		 "instead, specify \"%s\"",
 		 PERMIT_MX_BACKUP, var_mail_name, VAR_RELAY_DOMAINS);
     }
 
@@ -3905,7 +3905,7 @@ static int reject_maps_rbl(SMTPD_STATE *state)
      * Restriction reject_maps_rbl is deprecated as of Postfix 2.1.
      */
     msg_warn("support for restriction \"%s\" has been removed in %s 3.9; "
-	     "use \"%s domain-name\" instead",
+	     "instead, specify \"%s domain-name\"",
 	     REJECT_MAPS_RBL, var_mail_name, REJECT_RBL_CLIENT);
 
     reject_server_error(state);
@@ -4487,8 +4487,8 @@ static int generic_checks(SMTPD_STATE *state, ARGV *restrictions,
 	    }
 	} else if (strcasecmp(name, PERMIT_NAKED_IP_ADDR) == 0) {
 	    /* permit_naked_ip_addr is deprecated as of Postfix 2.0. */
-	    msg_warn("restriction %s has been removed in %s 3.9;"
-		     " use %s or %s instead",
+	    msg_warn("support for restriction \"%s\" has been removed in %s"
+		     " 3.9; instead, specify \"%s\" or \"%s\"",
 		     PERMIT_NAKED_IP_ADDR, var_mail_name,
 		     PERMIT_MYNETWORKS, PERMIT_SASL_AUTH);
 	    reject_server_error(state);