move from real users to passwd file

mail-server/dovecot.nix

@@ -16,7 +16,7 @@
 
 { config, pkgs, lib, ... }:
 
-with (import ./common.nix { inherit config; });
+with (import ./common.nix { inherit config lib; });
 
 let
   cfg = config.mailserver;
@@ -31,6 +31,7 @@ in
       enable = true;
       enableImap = enableImap;
       enablePop3 = enablePop3;
+      enablePAM = false;
       mailGroup = vmailGroupName;
       mailUser = vmailUserName;
       mailLocation = dovecot_maildir;
@@ -74,6 +75,11 @@ in
           mail_plugins = $mail_plugins sieve
         }
 
+        passdb {
+          driver = passwd-file
+          args = ${passwdFile}
+        }
+
         service auth {
           unix_listener /var/lib/postfix/queue/private/auth {
             mode = 0660