--- a/lib/config.tmpl
+++ b/lib/config.tmpl
@@ -22,16 +22,16 @@
 [% download_more = "${toplink}releases/#$releaseversion" %]
 [%# releases.mozilla.org disabled, see bug 871120 %]
 [%# download_allfiles = "http://releases.mozilla.org/pub/seamonkey/releases/$releaseversion/" %]
 [% download_allfiles = "https://archive.mozilla.org/pub/seamonkey/releases/$releaseversion/" %]
 [% download_win_mb = 40 %]
 [% download_linux_mb = 51 %]
 [% download_mac_mb = 49 %]
 
-[% betabaseversion = '2.53.11' %]
+[% betabaseversion = '2.53.12' %]
 [% betabetaversion = '1' %]
 [% betaversion = "${betabaseversion}b${betabetaversion}" %]
 [% betaname = "SeaMonkey ${betabaseversion} Beta ${betabetaversion}" %]
 
 [% develbaseversion = '2.68' %]
 [% develversion = "${develbaseversion}a1" %]
 [% develdownloadbase = 'https://archive.mozilla.org/pub/seamonkey/nightly/latest-comm-central-trunk' %]

--- a/lib/sitemap.xml
+++ b/lib/sitemap.xml
@@ -8,16 +8,19 @@ http://www.damowmow.com/portal/ (use the
 
 <site title="SeaMonkey Project" url="http://seamonkey-project.org">
 
   <page url="." title="Home" id="home" />
 
   <page url="news" title="News" id="news" />
 
   <page url="releases/" title="Download and Releases" id="releases">
+    <page url="releases/2.53.12b1" title="2.53.12 Beta 1" id="2.53.12b1" hide="false">
+      <page url="releases/seamonkey2.53.12/" title="Release Notes" id="seamonkey2.53.12"/>
+    </page>
     <page url="releases/2.53.11.1" title="2.53.11.1" id="2.53.11.1" hide="false">
       <page url="releases/seamonkey2.53.11.1/" title="Release Notes" id="seamonkey2.53.11.1"/>
     </page>
     <page url="releases/2.53.11" title="2.53.11" id="2.53.11" hide="true">
       <page url="releases/seamonkey2.53.11/" title="Release Notes" id="seamonkey2.53.11"/>
     </page>
     <page url="releases/2.53.11b1" title="2.53.11 Beta 1" id="2.53.11b1" hide="true"/>
     <page url="releases/2.53.10.2" title="2.53.10.2" id="2.53.10.2" hide="true">

--- a/src/dev/code-development.en.html
+++ b/src/dev/code-development.en.html
@@ -60,20 +60,20 @@ tree status</a> 24 hours a day.
 <p>
 You will need to complete the relevant instructions for preparing your OS for
 building SeaMonkey.
 </p>
 <ul>
 <li>Windows Build Prerequisites</li>
 <li>Linux Build Prerequisites</li>
 The following packages are required:<br>
-autoconf-2.13, python-2.7.18, nasm-2.14.x, rustc-1.38.0 (or 1.37.0 for 2.57), unzip-6.0 and zip-3.0<br>
-Note: For 2.53.x even though 1.38.0 is the minimum rustc version, 1.47.0 is the prefered one.<br><br>
+autoconf-2.13, python-2.7.18, nasm-2.14.x, clang-5, gcc-7, rustc-1.47.0 (or 1.37.0 for 2.57), unzip-6.0 and zip-3.0<br>
+Note: For 2.53.x even though 1.47.0 is the minimum rustc version, 1.58.1 is the prefered one.<br><br>
 The following development packages are required:<br>
-alsa-lib, dbus-glib, GConf2, gtk+-2.24.x, gtk+-3.24.x, libXt, pulseaudio-libs and yasm-1.3.0<br><br>
+alsa-lib, dbus-glib, GConf2, gtk+-3.24.x, libXt, pulseaudio-libs and yasm-1.3.0<br><br>
 <li>macOS Build Prerequisites</li>
 </ul>
 
 <h2 id="source">Getting the Source Code</h2>
 <p>There are currently three branches being worked on:</p>
 <ul>
 <li><a href="#stable">2.53.x</a></li>
 <li><a href="#future">2.57</a></li>

--- a/src/news.en.xml
+++ b/src/news.en.xml
@@ -2,16 +2,40 @@
 
 <!--
 non-ASCII characters must be DOUBLE-escaped;
 you can use Hixie's converter to get the entity codes
 http://www.damowmow.com/portal/ (use the "Indentify" field)
 -->
 
 <newsfeed title="SeaMonkey News" url="http://seamonkey-project.org/news">
+  <entry id="2022-04-23" showfront="true">
+    <headline>SeaMonkey 2.53.12 Beta 1 released</headline>
+    <content type="html" xml:lang="en">
+<![CDATA[<p>
+SeaMonkey 2.53.12 Beta 1 is
+<a href="releases/2.53.12b1">now available for free download</a> on the
+SeaMonkey website.
+</p>
+<p>
+2.53.12 will be an incremental update on the 2.53.x branch and incorporates a
+number of enhancements, changes and fixes to the application as well as those
+from the underlying platform code. NPAPI plugin support has been removed, as
+also has support for building with clang 4 and gcc 6. <b>Before installing it
+make a full backup of your profile and thoroughly read and follow the
+<a href="releases/seamonkey2.53.12/">Release Notes</a></b>. We encourage testers
+to <a href="dev/get-involved">get involved</a> in discussing and reporting
+problems as well as further improving the product.
+</p>
+<p>
+SeaMonkey 2.53.12 Beta 1 is available in 23 languages, for Windows, macOS x64
+and Linux.
+</p>]]>
+    </content>
+  </entry>
   <entry id="2022-03-25" showfront="true">
     <headline>SeaMonkey 2.53.11.1 released</headline>
     <content type="html" xml:lang="en">
 <![CDATA[<p>
 The SeaMonkey project is proud to present SeaMonkey 2.53.11.1: The new release
 of the all-in-one Internet suite is
 <a href="http://www.seamonkey-project.org/releases/">available for download
 now</a>! 2.53.11.1 is a minor incremental update from the 2.53.x branch and
@@ -44,17 +68,17 @@ href="doc/screenshots">screen shots</a>!
 href="https://www.seamonkey-project.org/">www.seamonkey-project.org</a>.
 </p>
 <p>
 We encourage users to <a href="dev/get-involved">get involved</a> in discussing
 and reporting problems as well as further improving the product.
 </p>]]>
     </content>
   </entry>
-  <entry id="2022-03-02" showfront="true">
+  <entry id="2022-03-02" showfront="false">
     <headline>SeaMonkey 2.53.11 released</headline>
     <content type="html" xml:lang="en">
 <![CDATA[<p>
 The SeaMonkey project is proud to present SeaMonkey 2.53.11: The new release of
 the all-in-one Internet suite is
 <a href="http://www.seamonkey-project.org/releases/">available for download
 now</a>! 2.53.11 is an incremental update from the 2.53.x branch and
 incorporates a number of changes, improvements to message filtering,

copy from src/releases/2.53.11.1.en.html
copy to src/releases/2.53.12b1.en.html
--- a/src/releases/2.53.11.1.en.html
+++ b/src/releases/2.53.12b1.en.html
@@ -1,17 +1,17 @@
 [%- PROCESS release.tmpl -%]
-[%- smversion = '2.53.11.1' -%]
-[%- prettyversion = '2.53.11.1' -%]
-[%- relnoteversion = '2.53.11.1' -%]
+[%- smversion = '2.53.12b1' -%]
+[%- prettyversion = '2.53.12 Beta 1' -%]
+[%- relnoteversion = '2.53.12' -%]
 [%- mirrorred = false -%]
 [%- uselongversion = false -%]
 [%- usefulldetails = true -%]
-[%- releasedate = "March 25, 2022" -%]
-[%- srcsize = "275" -%]
+[%- releasedate = "April 23, 2022" -%]
+[%- srcsize = "276" -%]
 [%- l10nsrcsize = "13" -%]
 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
 <html lang="en">
 <head>
 
 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
 <meta http-equiv="Content-Language" content="en">
 <meta http-equiv="Content-Style-Type" content="text/css">
@@ -98,19 +98,19 @@
    )
 %]
 [% INCLUDE downloads_table %]
 </div>
 
 <h2 id="source">Source code</h2>
 <div class="section">
   <p>The source code is available either as a tar package or from the
-    <a href="https://gitlab.com/seamonkey-project/seamonkey-2.53-comm/tree/2_53_11_1_final/">comm source repository</a>,
-    <a href="https://gitlab.com/seamonkey-project/seamonkey-2.53-mozilla/tree/2_53_11_1_final/">mozilla source repository</a> and
-    <a href="https://gitlab.com/seamonkey-project/seamonkey-2.53-l10n/tree/2_53_11_1_final/">l10n source repository</a> on GitLab.
+    <a href="https://gitlab.com/seamonkey-project/seamonkey-2.53-comm/tree/2_53_12_beta_01/">comm source repository</a>,
+    <a href="https://gitlab.com/seamonkey-project/seamonkey-2.53-mozilla/tree/2_53_12_beta_01/">mozilla source repository</a> and
+    <a href="https://gitlab.com/seamonkey-project/seamonkey-2.53-l10n/tree/2_53_12_beta_01/">l10n source repository</a> on GitLab.
   </p>
 
   <ul>
     <li id="tarball"><a href="[% INCLUDE download_file path="source/seamonkey-${smversion}.source.tar.xz" %]">Source
       Code Tarball</a> (xz, [% srcsize %] MB) - note that it doesn't unpack a
       subdirectory itself, so create a directory to unpack it in.
     </li>
 

--- a/src/releases/index.en.html
+++ b/src/releases/index.en.html
@@ -1,17 +1,17 @@
 [%- PROCESS release.tmpl -%]
 [%- smversion = releaseversion -%]
 [%- prettyversion = smversion -%]
 [%- relnoteversion = releaserelnoteversion -%]
 [%- mirrorred = false -%]
 [%- uselongversion = false -%]
 [%- usefulldetails = true -%]
 [%- releasedate = "March 25, 2022" -%]
-[%- betareleasedate = "January 30, 2022" -%]
+[%- betareleasedate = "April 23, 2022" -%]
 [%- srcsize = "275" -%]
 [%- l10nsrcsize = "13" -%]
 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
 <html lang="en">
 <head>
 
 <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
 <meta http-equiv="Content-Language" content="en">
@@ -194,17 +194,18 @@ For some legacy platforms like PPC Mac, 
 support. There are however independent projects that continue to support
 some of these platforms. To learn more, see <a href="legacy">Latest Releases
 for Legacy Platforms</a>.
 </p>
 
 <div class="para" id="old">
   <p>Previously released versions of SeaMonkey:</p>
   <ul class="snav">
-    <!-- <li><a href="2.53.11.1">2.53.11.1</a></li> -->
+    <!-- <li><a href="2.53.12b1">2.53.12 Beta 1</a></li> -->
+    <li><a href="2.53.11.1">2.53.11.1</a></li>
     <li><a href="2.53.11">2.53.11</a></li>
     <li><a href="2.53.11b1">2.53.11 Beta 1</a></li>
     <li><a href="2.53.10.2">2.53.10.2</a></li>
     <li><a href="2.53.10.1">2.53.10.1</a></li>
     <li><a href="2.53.10">2.53.10</a></li>
     <li><a href="2.53.10b1">2.53.10 Beta 1</a></li>
     <li><a href="2.53.9.1">2.53.9.1</a></li>
     <li><a href="2.53.9">2.53.9</a></li>

--- a/src/releases/legacy.en.html
+++ b/src/releases/legacy.en.html
@@ -21,16 +21,17 @@
     Requirements</a>). We do not support any of the applications and versions
     listed below. If your operating system or computer is no longer supported
     by official SeaMonkey releases, the only way to continue using officially
     supported SeaMonkey versions is to upgrade your operating system and/or
     computer.</p>
 </div>
 
 <ul>
+  <li>The last version supporting the Flash NPAPI plugin was SeaMonkey 2.53.6.</li>
   <li>The last version supporting Windows XP/Server 2003 and Vista/Server 2008 was SeaMonkey 2.49.5.</li>
   <li>The last version supporting plugins other than Flash on Windows and Linux was SeaMonkey 2.49.5.</li>
   <li>The last version with ALSA support on Linux was SeaMonkey 2.49.5.</li>
   <li>The last version supporting plugins other than Flash under macOS was SeaMonkey 2.49.4.</li>
   <li>The last version with gtk2 support on Linux was SeaMonkey 2.48.</li>
   <li>The last version with Mac OS 10.8 support was SeaMonkey 2.40.</li>
   <li>The last version for Windows with support for older CPUs not supporting the SSE2 instruction set was SeaMonkey 2.40.</li>
   <li>The last version with Mac OS 10.5 support was SeaMonkey 2.13.</li>

copy from src/releases/seamonkey2.53.11.1/index.en.html
copy to src/releases/seamonkey2.53.12/index.en.html
--- a/src/releases/seamonkey2.53.11.1/index.en.html
+++ b/src/releases/seamonkey2.53.12/index.en.html
@@ -22,18 +22,18 @@
 <p>
 <font color="#ff0000"><b>You MUST absolutely do a full backup of your profile
 before upgrading from a version earlier than SeaMonkey 2.53.1. This version of
 SeaMonkey makes changes to your profile that can't be reverted in cases where
 you need to go back to the older version.</b></font>
 </p>
 
 <p>
-<font color="#ff0000"><b>Automatic upgrades from previous 2.53.x versions are
-enabled for this release.</b></font>
+<font color="#ff0000"><b>Automatic upgrades from previous 2.53.x beta versions
+are enabled for this release.</b></font>
 </p>
 </div>
 
 <div class="key-point">
 <p>The Mozilla backend code SeaMonkey is based on, now usually incorporates
 breaking changes in every release. This is especially true for the Mozilla Gecko
 add-ons code and the JavaScript interpreter. Consequently, some older extensions
 <em>may</em> no longer function properly. If you experience any problems please
@@ -82,25 +82,64 @@ and known issues for [% rnote.basename %
 These notes are updated when we receive feedback, so please check back
 for new information.
 </p>
 </div>
 
 <h2 id="new">What's New in [% rnote.basename %]</h2>
 <div class="section">
 <p>
-[% rnote.basename %] contains (among other changes) the following changes relative to
+[% rnote.basename %] contains (among other changes) the following major changes relative to
 <a href="../seamonkey[% rnote.relativeto.version %]/#new">[% rnote.relativeto.name %]</a>:
 </p>
 <ul>
-  <li>Fix edge case when setting IntersectionObserver threshold <a
-    href="https://bugzilla.mozilla.org/show_bug.cgi?id=1758291">bug 1758291</a>.
+  <li>Format Toolbar forgets its hidden status when switching to other view
+    modes <a
+    href="https://bugzilla.mozilla.org/show_bug.cgi?id=1719020">bug 1719020</a>.
+  </li>
+  <li>Remove obsolete plugin code from SeaMonkey <a
+    href="https://bugzilla.mozilla.org/show_bug.cgi?id=1762733">bug 1762733</a>.
+  </li>
+  <li>Fix a few strict warnings in SeaMonkey <a
+    href="https://bugzilla.mozilla.org/show_bug.cgi?id=1755553">bug 1755553</a>.
+  </li>
+  <li>Remove Run Flash from Site permissions and page info <a
+    href="https://bugzilla.mozilla.org/show_bug.cgi?id=1758289">bug 1758289</a>.
+  </li>
+  <li>Use fixIterator and replace use of removeItemAt in FilterListDialog <a
+    href="https://bugzilla.mozilla.org/show_bug.cgi?id=1756359">bug 1756359</a>.
+  </li>
+  <li>Remove RDF usage in tabmail.js <a
+    href="https://bugzilla.mozilla.org/show_bug.cgi?id=1758282">bug 1758282</a>.
   </li>
-  <li>OAuth2 prefs should use realuserName instead of username <a
-    href="https://bugzilla.mozilla.org/show_bug.cgi?id=1518126">bug 1518126</a>.
+  <li>Implement 'Edit Template' and 'New Message From Template' commands and UI
+    <a
+    href="https://bugzilla.mozilla.org/show_bug.cgi?id=1759376">bug 1759376</a>.
+  </li>
+  <li>[SM] Implement 'Edit Draft' command and hide it when not in a draft folder
+    (port Thunderbird bug 1106412) <a
+    href="https://bugzilla.mozilla.org/show_bug.cgi?id=1256716">bug 1256716</a>.
+  </li>
+  <li>Messages in Template folder need "Edit Template" button in header (like
+    for Drafts) <a
+    href="https://bugzilla.mozilla.org/show_bug.cgi?id=80280">bug 80280</a>.
+  </li>
+  <li>Refactor and simplify the feed Subscribe dialog options updates <a
+    href="https://bugzilla.mozilla.org/show_bug.cgi?id=1420473">bug 1420473</a>.
+  </li>
+  <li>Add system memory and disk size and placeDB page limit to about:support <a
+    href="https://bugzilla.mozilla.org/show_bug.cgi?id=1753729">bug 1753729</a>.
+  </li>
+</ul>
+<p>
+The following bugs were fixed in our branch of the Gecko source code only:
+</p>
+<ul>
+  <li>Remove warning about missing plugins in SeaMonkey 2.53 and 2.57 <a
+    href="https://bugzilla.mozilla.org/show_bug.cgi?id=1755558">bug 1755558</a>.
   </li>
 </ul>
 <p>
 [% rnote.basename %] contains (among other changes) the following major changes relative to
 <a href="../seamonkey[% rnote.relativeto.stable.version %]/#new">[% rnote.relativeto.stable.name %]</a>:
 </p>
 
 <ul>

copy from src/releases/seamonkey2.53.11.1/relnote.var
copy to src/releases/seamonkey2.53.12/relnote.var
--- a/src/releases/seamonkey2.53.11.1/relnote.var
+++ b/src/releases/seamonkey2.53.12/relnote.var
@@ -1,14 +1,14 @@
-[%- rnote.baseversion = "2.53.11.1" -%]
-[%- rnote.basename = "SeaMonkey 2.53.11.1" -%]
-[%- rnote.version = "2.53.11.1" -%]
-[%- rnote.name = "SeaMonkey 2.53.11.1" -%]
-[%- rnote.relativeto.version = "2.53.11" -%]
-[%- rnote.relativeto.name = "SeaMonkey 2.53.11" -%]
+[%- rnote.baseversion = "2.53.12" -%]
+[%- rnote.basename = "SeaMonkey 2.53.12" -%]
+[%- rnote.version = "2.53.12b1" -%]
+[%- rnote.name = "SeaMonkey 2.53.12 Beta 1" -%]
+[%- rnote.relativeto.version = "2.53.11.1" -%]
+[%- rnote.relativeto.name = "SeaMonkey 2.53.11.1" -%]
 [%- rnote.relativeto.stable.version = "2.49.5" -%]
 [%- rnote.relativeto.stable.name = "SeaMonkey 2.49.5" -%]
 [%- changes.sm.ver = "253" -%]
 [%- changes.sm.tm = "2.53"-%]
 [%- changes.tb.tm = "60.8.0" -%]
 [%- changes.sec.tm = "60.8" -%]
-[%- changes.fx.esr = "91.7" -%]
-[%- changes.tb.esr = "91.7" -%]
+[%- changes.fx.esr = "91.8" -%]
+[%- changes.tb.esr = "91.8" -%]