It might be an workaround for some firewalls blocking Postfix SMTP client:
Here is the case I worked out: Problem - Postfix (SMTP Client) receives 500 5.3.3 Unrecognized command from the SMTP Server. Of course both Postfix and Exchange (in this example) know smtp commands. Cause: - A firewall in the middle is altering SMTP syntax. Workaround: - Replacing the hard error with a soft error (400 in smtp_reply_filter) causes Postfix SMTP client to retry and deliver the messages. I did not debug the second retry and see if Postfix client is sending the message in a different way - possible it does. Suggestion: - In other words, with the smtp_reply_filter listed below, the delivery chances are significantly increased and might be a good idea to implement a smtp_(cisco?)_workaround_(harderror?) = yes/no. Here is my smtp_reply_filter (first in line works in real case, the others are assumptions) /^500 5\.3\.3 Unrecogni[zs]ed command/ 400 4.3.3 Message not accepted by Exchange. Retrying later /^500 unrecogni[zs]ed command/ 400 Message not accepted by Exim. Retrying later /^502 5\.5\.2 Error: command not recognized/ 402 5.5.2 Message not accepted by Postfix. Retrying later /^500 Syntax error/ 400 Message not accepted by Lotus. Retrying later Marius. -----Original Message----- From: owner-postfix-us...@postfix.org [mailto:owner-postfix-us...@postfix.org] On Behalf Of Wijatmoko U. Prayitno Sent: Monday, June 2, 2014 12:00 PM To: postfix-users@postfix.org Subject: Re: Suggestion On Mon, 2 Jun 2014 11:38:27 +0300 "Marius Gologan" <marius.golo...@gmail.com> wrote: > Where can I make a suggestion? > What kind suggestion? You can post here..
