treewide: impermanence configuration

hosts/mail/mail.nix

@@ -85,4 +85,52 @@ in
     smtp_destination_concurrency_limit = "20";
     header_size_limit = "4096000";
   };
+
+  environment.persistence."/persist".directories = [
+    {
+      directory = "/var/dkim";
+      user = "rspamd";
+      group = "rspamd";
+      mode = "0755";
+    }
+    {
+      directory = "/var/sieve";
+      user = "virtualMail";
+      group = "virtualMail";
+      mode = "0770";
+    }
+    {
+      directory = "/var/vmail";
+      user = "virtualMail";
+      group = "virtualMail";
+      mode = "0700";
+    }
+    {
+      directory = "/var/lib/rspamd";
+      user = "rspamd";
+      group = "rspamd";
+      mode = "0700";
+    }
+    {
+      directory = "/var/lib/redis-rspamd";
+      user = "redis-rspamd";
+      group = "redis-rspamd";
+      mode = "0700";
+    }
+    {
+      directory = "/var/lib/opendkim";
+      user = 221;
+      group = 221;
+      mode = "0700";
+    }
+    {
+      directory = "/var/lib/knot-resolver";
+      user = "knot-resolver";
+      group = "knot-resolver";
+      mode = "0770";
+    }
+    "/var/lib/dhparams"
+    "/var/lib/dovecot"
+    "/var/lib/postfix"
+  ];
 }