Reorganize imports

With the growing number of option refactors centralize the module import
within the mail-server directory.

Also group deprecations by release, so we can eventually yank them in
bulk after a while.

default.nix

@@ -1524,6 +1524,9 @@ in
   };
 
   imports = [
+    ./mail-server
+
+    # NixOS 25.05
     (mkRemovedOptionModule [ "mailserver" "fullTextSearch" "maintenance" "enable" ] ''
       This option is not needed for fts-flatcurve
     '')
@@ -1549,19 +1552,6 @@ in
     (mkRemovedOptionModule [ "mailserver" "rebootAfterKernelUpgrade" "method" ] ''
       Use `system.autoUpgrade` instead.
     '')
-    ./mail-server/assertions.nix
-    ./mail-server/borgbackup.nix
-    ./mail-server/rsnapshot.nix
-    ./mail-server/clamav.nix
-    ./mail-server/monit.nix
-    ./mail-server/users.nix
-    ./mail-server/environment.nix
-    ./mail-server/networking.nix
-    ./mail-server/systemd.nix
-    ./mail-server/dovecot.nix
-    ./mail-server/postfix.nix
-    ./mail-server/rspamd.nix
-    ./mail-server/kresd.nix
     (mkRemovedOptionModule [ "mailserver" "policydSPFExtraConfig" ] ''
       SPF checking has been migrated to Rspamd, which makes this config redundant. Please look into the rspamd config to migrate your settings.
       It may be that they are redundant and are already configured in rspamd like for skip_addresses.
@@ -1575,13 +1565,8 @@ in
     (mkRemovedOptionModule [ "mailserver" "smtpdForbidBareNewline" ] ''
       The workaround for the SMTP Smuggling attack is default enabled in Postfix >3.9. Use `services.postfix.config.smtpd_forbid_bare_newline` if you need to deviate from its default.
     '')
-    (mkRenamedOptionModule [ "mailserver" "dkimSigning" ] [ "mailserver" "dkim" "enable" ])
+
-    (mkRenamedOptionModule [ "mailserver" "dkimKeyDirectory" ] [ "mailserver" "dkim" "keyDirectory" ])
+    # NixOS 25.11
-    (mkRenamedOptionModule
-      [ "mailserver" "dkimSelector" ]
-      [ "mailserver" "dkim" "defaults" "selector" ]
-    )
-    (mkRenamedOptionModule [ "mailserver" "dkimKeyType" ] [ "mailserver" "dkim" "defaults" "keyType" ])
     (mkRenamedOptionModule [ "mailserver" "dmarcReporting" "domain" ] [ "mailserver" "systemDomain" ])
     (mkRenamedOptionModule
       [ "mailserver" "dmarcReporting" "organizationName" ]
@@ -1597,6 +1582,7 @@ in
       The name in the `FROM` field for DMARC report now uses the `mailserver.systemName`.
     '')
 
+    # NixOS 26.05
     (mkRemovedOptionModule [ "mailserver" "certificateDomains" ] ''
       Configure `security.acme.certs.''${config.mailserver.fqdn}.extraDomains` instead.
     '')
@@ -1607,5 +1593,13 @@ in
     (mkRenamedOptionModule [ "mailserver" "acmeCertificateName" ] [ "mailserver" "x509" "useACMEHost" ])
     (mkRenamedOptionModule [ "mailserver" "certificateFile" ] [ "mailserver" "x509" "certificateFile" ])
     (mkRenamedOptionModule [ "mailserver" "keyFile" ] [ "mailserver" "x509" "privateKeyFile" ])
+
+    (mkRenamedOptionModule [ "mailserver" "dkimSigning" ] [ "mailserver" "dkim" "enable" ])
+    (mkRenamedOptionModule [ "mailserver" "dkimKeyDirectory" ] [ "mailserver" "dkim" "keyDirectory" ])
+    (mkRenamedOptionModule
+      [ "mailserver" "dkimSelector" ]
+      [ "mailserver" "dkim" "defaults" "selector" ]
+    )
+    (mkRenamedOptionModule [ "mailserver" "dkimKeyType" ] [ "mailserver" "dkim" "defaults" "keyType" ])
   ];
 }

mail-server/default.nix

@@ -0,0 +1,17 @@
+{
+  imports = [
+    ./assertions.nix
+    ./borgbackup.nix
+    ./rsnapshot.nix
+    ./clamav.nix
+    ./monit.nix
+    ./users.nix
+    ./environment.nix
+    ./networking.nix
+    ./systemd.nix
+    ./dovecot.nix
+    ./postfix.nix
+    ./rspamd.nix
+    ./kresd.nix
+  ];
+}