patrick ben koetter bstateofmindde jordan 3508 patrick ben koetter wrote jordan hello strange problem using postfix using email program request tracker company several different email domains another company hosts email relayhost setup new outgoing email email hosting company email domains split across two different servers due merger another company basically send email one domain company1com without problem domain require stmp authentication since hosted server try send email domain rejected 553 error message states 553 sorry domain isnt list allowed rcpthosts 571 reply rcpt command pulling varlogmailinfo happening postfix sending helo instead ehlo even attempting use authentication confirmed tcpdump remote server introduce promote esmtp smtp banner brick output smtp session telnet smtpcompany1com 25 trying 2315 connected mymailemailhostcom escape character 220 server really introduce would smtp client know server supports esmtp way server tell client supports using string esmtp smtp banner eg like 220 mailstateofmindde esmtp postfix way client knows server supports esmtp go ehlo itapache otherwise client must use least common denominator ie smtp tell server issue esmtp banner postfix smtp client use ehlo brick book postfix saslfinger debugging smtp auth fri 08 aug 2008 131435 0100 postfix using correct command helo vs ehlo