Dear list members, I have the following problem:
A 3rd party e-mail provider refuses the HELO/EHLO command if it doesn't contain a valid FQDN address (which is acceptable from their point of view). They refuse it with a 501 (permanent) error, which means according to [1]: "[...] In this case, the sending MTA server should not queue the message, but delete it from its queue and send back an NDR (Non-Delivery-Response) to the sender, informing of such error." The problem is, in spite of the above mentioned, Postfix (and BSD sendmail also) puts the letter into the mail queue as it was deferred and tries to re- send it continuously. I tested it with the following: $ /> telnet server29.citromail.hu smtp Trying 91.83.45.29... Connected to server29.citromail.hu. Escape character is '^]'. 220 server29 mfiltro ESMTP server ready HELO google.local 501 HELO requires FQDN address Connection closed by foreign host. So far this is ok. But after I sent a message with "sendmail x...@citromail.hu", the following shows up in the mail queue: D82A21807CB 300 Sat Aug 24 15:52:28 root@xxxxxx.local (lost connection with server27.citromail.hu[91.83.45.27] while performing the HELO handshake) In Postfix the "soft_bounce" parameter is set to "no". I know that the problem can be easily circumvented by setting a proper FQDN, but I want to know the root cause why Postfix (and the plain sendmail) puts the letter into the queue as a deferred one. Thank you for your reply, Ákos Szőts [1]: http://en.redinskala.com/extended-status-codes-smtp/
