Merge branch 'sieve-extensions' into 'master'

Add configuration for the sieve extensions

See merge request simple-nixos-mailserver/nixos-mailserver!294

default.nix

@@ -743,6 +743,18 @@ in
       '';
     };
 
+    sieveExtensions = mkOption {
+      type = types.listOf types.str;
+      default = [];
+      example = [ "+editheader" ];
+      description = ''
+        Enabled extensions for the sieve interpreter. See
+        https://doc.dovecot.org/configuration_manual/sieve/#sieve-plugins .
+        For an example usage see
+        https://doc.dovecot.org/configuration_manual/sieve/configuring_auto_forward_sender_address/
+      '';
+    };
+
     virusScanning = mkOption {
       type = types.bool;
       default = false;

mail-server/dovecot.nix

@@ -326,6 +326,7 @@ in
 
           sieve_pipe_bin_dir = ${pipeBin}/pipe/bin
 
+          sieve_extensions = ${lib.concatStringsSep " " cfg.sieveExtensions}
           sieve_global_extensions = +vnd.dovecot.pipe +vnd.dovecot.environment
         }