I have recently noticed that some of our internal mailer scripts are causing Dovecot-LDA to generate Mailer Delivery Subsystem messages. The following Dovecot-LDA message is generated:

---- Message body ---- Your message was automatically rejected by Dovecot Mail Delivery Agent. The following reason was given: Unknown error ---- Message body ----

---- Message header ---- Return-Path: <MAILER-DAEMON> Delivered-To: bounces@xxxxx Received: by mymachine.xxxxx (Postfix, from userid 5000) id 5772568300; Mon, 14 Jan 2008 18:00:56 +1100 (EST) Message-ID: dovecot-1200294055-774265-0@mymachine Date: Mon, 14 Jan 2008 18:00:55 +1100 From: Mail Delivery Subsystem noreply@xxxxx To: bounces@xxxxx MIME-Version: 1.0 Content-Type: multipart/report; report-type=disposition-notification; boundary="21506/mailfilter02" Subject: Automatically rejected mail Auto-Submitted: auto-replied (rejected) Precedence: bulk ---- Message header ----

Initially I thought these were being caused by Delivery-Receipt requests, however have since tested this and is not the case. I have tried to snoop through the logs (unfortunately on a very busy mail hub) using the Message-ID, however this doesn't seem to lead me back to the original message - only the MDA notification. I can only ascertain that its isolated to our scripts, as the bounces@ address is specifically used by them.

Any ideas what would cause/trigger the "Unknown error" automatic rejects ?

System config is -Postfix 2.3.4 with MySQL backend -Dovecot 1.0.rc26 with MySQL backend, using only deliver.

All mail deliveries are otherwise fine.

Regards

Dean Manners