diff --git a/default.nix b/default.nix
index 31aa12b..21c38e3 100644
--- a/default.nix
+++ b/default.nix
@@ -620,6 +620,14 @@ in
       '';
     };
 
+    recipientDelimiter = mkOption {
+      type = types.str;
+      default = "+";
+      description = ''
+        Configure the recipient delimiter.
+      '';
+    };
+
     redis = {
       address = mkOption {
         type = types.str;
diff --git a/mail-server/dovecot.nix b/mail-server/dovecot.nix
index c4811e1..293aaa6 100644
--- a/mail-server/dovecot.nix
+++ b/mail-server/dovecot.nix
@@ -191,7 +191,7 @@ in
           }
         }
 
-        recipient_delimiter = +
+        recipient_delimiter = ${cfg.recipientDelimiter}
         lmtp_save_to_detail_mailbox = ${cfg.lmtpSaveToDetailMailbox}
 
         protocol lmtp {
diff --git a/mail-server/postfix.nix b/mail-server/postfix.nix
index 971c833..618d6c5 100644
--- a/mail-server/postfix.nix
+++ b/mail-server/postfix.nix
@@ -160,7 +160,7 @@ in
       config = {
         # Extra Config
         mydestination = "";
-        recipient_delimiter = "+";
+        recipient_delimiter = cfg.recipientDelimiter;
         smtpd_banner = "${fqdn} ESMTP NO UCE";
         disable_vrfy_command = true;
         message_size_limit = toString cfg.messageSizeLimit;