diff --git a/.hydra/declarative-jobsets.nix b/.hydra/declarative-jobsets.nix
index 5273cc2..130df05 100644
--- a/.hydra/declarative-jobsets.nix
+++ b/.hydra/declarative-jobsets.nix
@@ -61,8 +61,8 @@ let
 
   desc = prJobsets // {
     "master" = mkFlakeJobset "master";
-    "nixos-20.09" = mkJobset "nixos-20.09";
     "nixos-21.05" = mkJobset "nixos-21.05";
+    "nixos-21.11" = mkJobset "nixos-21.11";
   };
 
   log = {
diff --git a/README.md b/README.md
index 647dcfa..c77cf24 100644
--- a/README.md
+++ b/README.md
@@ -8,18 +8,18 @@
 For each NixOS release, we publish a branch. You then have to use the
 SNM branch corresponding to your NixOS version.
 
+* For NixOS 21.11
+   - Use the [SNM branch `nixos-21.11`](https://gitlab.com/simple-nixos-mailserver/nixos-mailserver/-/tree/nixos-21.11)
+   - [Documentation](https://nixos-mailserver.readthedocs.io/en/nixos-21.11/)
+   - [Release notes](https://nixos-mailserver.readthedocs.io/en/nixos-21.11/release-notes.html#nixos-21-11)
 * For NixOS 21.05
    - Use the [SNM branch `nixos-21.05`](https://gitlab.com/simple-nixos-mailserver/nixos-mailserver/-/tree/nixos-21.05)
    - [Documentation](https://nixos-mailserver.readthedocs.io/en/nixos-21.05/)
    - [Release notes](https://nixos-mailserver.readthedocs.io/en/nixos-21.05/release-notes.html#nixos-21-05)
-* For NixOS 20.09
-   - Use the [SNM branch `nixos-20.09`](https://gitlab.com/simple-nixos-mailserver/nixos-mailserver/-/tree/nixos-20.09)
-   - [Documentation](https://nixos-mailserver.readthedocs.io/en/nixos-20.09/)
-   - [Release notes](https://nixos-mailserver.readthedocs.io/en/nixos-20.09/release-notes.html#nixos-20-09)
 * For NixOS unstable
    - Use the [SNM branch `master`](https://gitlab.com/simple-nixos-mailserver/nixos-mailserver/-/tree/master)
    - [Documentation](https://nixos-mailserver.readthedocs.io/en/latest/)
-   - This branch is currently supporting the NixOS release 21.05 but
+   - This branch is currently supporting the NixOS release 21.11 but
      we could remove this support on any NixOS unstable breaking
      change.
 
diff --git a/docs/release-notes.rst b/docs/release-notes.rst
index fce2abf..cf9fad2 100644
--- a/docs/release-notes.rst
+++ b/docs/release-notes.rst
@@ -1,6 +1,21 @@
 Release Notes
 =============
 
+NixOS 21.11
+-----------
+
+- Switch default DKIM body policy from simple to relaxed
+  (`merge request <https://gitlab.com/simple-nixos-mailserver/nixos-mailserver/-/merge_requests/247>`__)
+- Ensure locally-delivered mails have the X-Original-To header
+  (`merge request <https://gitlab.com/simple-nixos-mailserver/nixos-mailserver/-/merge_requests/243>`__)
+- NixOS Mailserver options are detailed in the `documentation
+  <https://nixos-mailserver.readthedocs.io/en/latest/options.html>`__
+- New options ``dkimBodyCanonicalization`` and
+  ``dkimHeaderCanonicalization``
+- New option ``certificateDomains`` to generate certificate for
+  additional domains (such as ``imap.example.com``)
+
+
 NixOS 21.05
 -----------
 
diff --git a/flake.lock b/flake.lock
index f3ec998..3580349 100644
--- a/flake.lock
+++ b/flake.lock
@@ -46,11 +46,27 @@
         "type": "indirect"
       }
     },
+    "nixpkgs-21_11": {
+      "locked": {
+        "lastModified": 1638371214,
+        "narHash": "sha256-0kE6KhgH7n0vyuX4aUoGsGIQOqjIx2fJavpCWtn73rc=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "a640d8394f34714578f3e6335fc767d0755d78f9",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "ref": "nixos-21.11",
+        "type": "indirect"
+      }
+    },
     "root": {
       "inputs": {
         "blobs": "blobs",
         "nixpkgs": "nixpkgs",
         "nixpkgs-21_05": "nixpkgs-21_05",
+        "nixpkgs-21_11": "nixpkgs-21_11",
         "utils": "utils"
       }
     },
diff --git a/flake.nix b/flake.nix
index 7d6dc4c..33e433e 100644
--- a/flake.nix
+++ b/flake.nix
@@ -5,13 +5,14 @@
     utils.url = "github:numtide/flake-utils";
     nixpkgs.url = "flake:nixpkgs/nixos-unstable";
     nixpkgs-21_05.url = "flake:nixpkgs/nixos-21.05";
+    nixpkgs-21_11.url = "flake:nixpkgs/nixos-21.11";
     blobs = {
       url = "gitlab:simple-nixos-mailserver/blobs";
       flake = false;
     };
   };
 
-  outputs = { self, utils, blobs, nixpkgs, nixpkgs-21_05 }: let
+  outputs = { self, utils, blobs, nixpkgs, nixpkgs-21_05, nixpkgs-21_11 }: let
     system = "x86_64-linux";
     pkgs = nixpkgs.legacyPackages.${system};
     # We want to test nixos-mailserver on several nixos releases
@@ -24,6 +25,10 @@
         name = "21_05";
         pkgs = nixpkgs-21_05.legacyPackages.${system};
       }
+      {
+        name = "21_11";
+        pkgs = nixpkgs-21_11.legacyPackages.${system};
+      }
     ];
     testNames = [
       "internal"