Hello all, I wanted to get the list's advice on a rather odd problem we've been experiencing on our Postfix mail relays. We are running Postfix 2.6.6 on Redhat Enterprise Linux 6.3. There are 3 Postfix mail relays which sit behind a Cisco ACE load balancer that performs round-robin load balancing.
We have a process whereby a plain text file contain alias mappings for a virtual domain is uploaded to our Postfix mail relays on a periodic basis (every few minutes depending on the number of new aliases). An incron job, which is triggered by the changes in the file, then rebuilds the virtual.db file for the virtual domains using make. The issue we are experiencing is that sometimes users will report that mail is occasionally rejected with a "550 5.1.1 <user@domain> : Recipient address rejected: User unknown (in reply to RCPT TO command);" I have used postmap as follows to verify if the alias resolves: postmap -q <user@domain> hash:/etc/postfix/postfix-out/virtual The above command returns the correct result on all 3 Postfix mail relays. However, we still experience the issue whereby mail is sometimes correctly delivered and other times we get the 550 error shown above. It's very puzzling and I have only a few ideas to go on: 1. Is rebuilding the virtual.db file frequently (every few minutes) causing Postfix to lose access temporarily to the aliases in that database causing the random lookup failures? 2. Is the version of Postfix (2.6.6) fairly old and may have some bugs that can cause this? Any info. or experience with any similar issues would be appreciated. Please let me know if you need further details on our configuration or relay architecture. Thanks everybody. Kind regards, Venkat M University of British Columbia
