diff --git a/.gitignore b/.gitignore
index 4120a67f..52207973 100644
--- a/.gitignore
+++ b/.gitignore
@@ -37,3 +37,4 @@ prof/
 .pytype/
 ~temp*
 *.sw[a-p]
+pyvenv.cfg
diff --git a/DESCRIPTION.rst b/DESCRIPTION.rst
index caa9e7a7..c41fb1da 100644
--- a/DESCRIPTION.rst
+++ b/DESCRIPTION.rst
@@ -45,7 +45,7 @@
 
 This is a server for SMTP and related MTA protocols,
 similar in utility to the standard library's |smtpd.py|_ module,
-but rewritten to be based on ``asyncio`` for Python 3.6+.
+but rewritten to be based on ``asyncio`` for Python 3.7+.
 
 Please visit the `Project Homepage`_ for more information.
 
diff --git a/MANIFEST.in b/MANIFEST.in
index c1397cf5..b7a588e1 100644
--- a/MANIFEST.in
+++ b/MANIFEST.in
@@ -1,3 +1,3 @@
 graft aiosmtpd
 include LICENSE NOTICE *.cfg *.ini *.py *.rst *.yml *.toml
-global-exclude *.py[oc] *.sw[a-p]
+global-exclude *.py[oc] *.sw[a-p] pyvenv.cfg
diff --git a/README.rst b/README.rst
index 2c1bab7d..48a753c7 100644
--- a/README.rst
+++ b/README.rst
@@ -55,13 +55,13 @@ Full documentation is available on |aiosmtpd rtd|_
 Requirements
 ============
 
-You need **at least Python 3.6** to use this library.
+You need **at least Python 3.7** to use this library.
 
 
 Supported Platforms
 -----------------------
 
-``aiosmtpd`` has been tested on **CPython** and |PyPy3.7|_
+``aiosmtpd`` has been tested on **CPython**>=3.7 and |PyPy|_>=3.7
 for the following platforms (in alphabetical order):
 
 * Cygwin (on Windows 10) [1]
@@ -69,6 +69,7 @@ for the following platforms (in alphabetical order):
 * OpenSUSE Leap 15 [2]
 * Ubuntu 18.04
 * Ubuntu 20.04
+* Ubuntu 22.04
 * Windows 10
 
   | [1] Supported only with Cygwin-provided CPython versions
@@ -77,8 +78,8 @@ for the following platforms (in alphabetical order):
 ``aiosmtpd`` *probably* can run on platforms not listed above,
 but we cannot provide support for unlisted platforms.
 
-.. |PyPy3.7| replace:: **PyPy3.7**
-.. _`PyPy3.7`: https://www.pypy.org/
+.. |PyPy| replace:: **PyPy**
+.. _`PyPy`: https://www.pypy.org/
 
 
 Installation
@@ -175,7 +176,7 @@ In general, the ``-e`` parameter to tox specifies one (or more) **testenv**
 to run (separate using comma if more than one testenv). The following testenvs
 have been configured and tested:
 
-* ``{py36,py37,py38,py39,pypy3}-{nocov,cov,diffcov,profile}``
+* ``{py37,py38,py39,py310,py311,pypy3}-{nocov,cov,diffcov,profile}``
 
   Specifies the interpreter to run and the kind of testing to perform.
 
diff --git a/aiosmtpd/__init__.py b/aiosmtpd/__init__.py
index fc683476..63a070cd 100644
--- a/aiosmtpd/__init__.py
+++ b/aiosmtpd/__init__.py
@@ -1,4 +1,4 @@
 # Copyright 2014-2021 The aiosmtpd Developers
 # SPDX-License-Identifier: Apache-2.0
 
-__version__ = "1.4.3.dev0"
+__version__ = "1.4.3rc1"
diff --git a/aiosmtpd/docs/NEWS.rst b/aiosmtpd/docs/NEWS.rst
index eea911da..3dece748 100644
--- a/aiosmtpd/docs/NEWS.rst
+++ b/aiosmtpd/docs/NEWS.rst
@@ -16,6 +16,20 @@ Fixed/Improved
 * A whole bunch of annotations
 
 
+1.4.3 (2022-12-16)
+==================
+
+Fixed/Improved
+--------------
+* Add compatibility for Python 3.10 and 3.11 (Closes #322)
+* Test matrix update (Closes #306)
+
+  * Drop Python 3.6, PyPy 3.6 (some) and MacOS 10
+  * Add Python 3.10 & 3.11, PyPy 3.7 & 3.8, Ubuntu 22.04, MacOS 11 & 12
+
+* Longer AUTOSTOP_DELAY especially for Windows (Closes #313)
+
+
 1.4.2 (2021-03-08)
 =====================
 
diff --git a/aiosmtpd/docs/controller.rst b/aiosmtpd/docs/controller.rst
index e43720bd..c1edc13d 100644
--- a/aiosmtpd/docs/controller.rst
+++ b/aiosmtpd/docs/controller.rst
@@ -21,6 +21,12 @@ In both cases, you need to pass a :ref:`handler <handlers>` to the ``SMTP``
 constructor.  Handlers respond to events that you care about during the SMTP
 dialog.
 
+.. important::
+
+  Consider running the controller in a separate Python process (e.g., using the
+  :mod:`multiprocessing` module) if you don't want your main Python process to be
+  blocked when aiosmtpd is handling extra-large emails.
+
 
 Using the controller
 ====================
diff --git a/setup.cfg b/setup.cfg
index e5409bdd..c4fe49c1 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -21,7 +21,6 @@ classifiers =
     Operating System :: POSIX :: BSD :: FreeBSD
     Operating System :: POSIX :: Linux
     Programming Language :: Python :: 3 :: Only
-    Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
@@ -34,7 +33,7 @@ classifiers =
 
 [options]
 zip_safe = false
-python_requires = ~=3.6
+python_requires = ~=3.7
 packages = find:
 include_package_data = true
 install_requires =
diff --git a/tox.ini b/tox.ini
index ae30ade7..423a1ed9 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,12 +1,11 @@
 [tox]
 minversion = 3.9.0
-envlist = qa, static, docs, py{36,37,38,39,py3}-{nocov,cov,diffcov}
+envlist = qa, static, docs, py{37,38,39,py3}-{nocov,cov,diffcov}
 skip_missing_interpreters = True
 
 [testenv]
 # One virtualenv per Python version
 envdir =
-    py36: {toxworkdir}/3.6
     py37: {toxworkdir}/3.7
     py38: {toxworkdir}/3.8
     py39: {toxworkdir}/3.9
@@ -45,11 +44,11 @@ deps =
 setenv =
     cov: COVERAGE_FILE={toxinidir}/_dump/.coverage
     nocov: PYTHONASYNCIODEBUG=1
-    py36: INTERP=py36
     py37: INTERP=py37
     py38: INTERP=py38
     py39: INTERP=py39
     py310: INTERP=py310
+    py311: INTERP=py311
     pypy3: INTERP=pypy3
     py: INTERP=py
 passenv =
@@ -110,14 +109,16 @@ commands =
     python -m flake8 aiosmtpd setup.py housekeep.py release.py
     check-manifest -v
     pytest -v --tb=short aiosmtpd/qa
-    pytype --keep-going --jobs auto .
+    # Disabled for now because pytype blows up in Windows
+    #pytype --keep-going --jobs auto .
 deps =
     colorama
     flake8>=5.0.4
     {[flake8_plugins]deps}
     pytest
     check-manifest
-    pytype
+    # Disabled for now because pytype blows up in Windows
+    #pytype
 
 [testenv:docs]
 basepython = python3