Make imap memory limit configurable

default.nix

@@ -712,6 +712,14 @@ in
       '';
     };
 
+    imapMemoryLimit = mkOption {
+      type = types.int;
+      default = 256;
+      description = ''
+        The memory limit for the imap service, in megabytes.
+      '';
+    };
+
     enableImapSsl = mkOption {
       type = types.bool;
       default = true;

mail-server/dovecot.nix

@@ -276,6 +276,10 @@ in
           mail_plugins = $mail_plugins imap_sieve
         }
 
+        service imap {
+	  vsz_limit = ${builtins.toString cfg.imapMemoryLimit} MB
+	}
+
         protocol pop3 {
           mail_max_userip_connections = ${toString cfg.maxConnectionsPerUser}
         }