Delivery Status Notifications - What is required from the remote MTA?

[Russell Jones]

Hi *, My google-foo is failing me at this point, so I turn to you all. I am using a standard Postfix setup and am sending messages via Thunderbird. I am choosing under the Options menu "Delivery Status Notification". The results: DSN's for email sent to gmail work fine DSN's for email sent to yahoo work fine DSN's for email sent to a local account on my mail server work fine There is one specific mail server though that I am not receiving "successful delivery" DSN's for, and I cannot figure out why. The following is the conversation log from my server to theirs: Nov 30 16:39:19 bigbertha postfix/cleanup[18162]: 78861CCFF: warning: header Subject: asasddsad from c-98-197-129-225.hsd1.tx.comcast.net[98.197.129.225]; from=<rjo...@eggycrew.com> to=<redacted> proto=ESMTP helo=<[192.168.2.3]> Nov 30 16:39:19 bigbertha postfix/qmgr[16356]: 78861CCFF: from=<rjo...@eggycrew.com>, size=805, nrcpt=1 (queue active) Nov 30 16:39:19 bigbertha postfix/smtpd[18337]: disconnect from c-98-197-129-225.hsd1.tx.comcast.net[98.197.129.225] Nov 30 16:39:21 bigbertha postfix/smtp[18341]: 78861CCFF: to=<redacted>, relay=redacted[redacted]:25, delay=2.5, delays=0.18/0/0.43/1.9, dsn=2.0.0, status=sent (250 +OK message queued for delivery.) Nov 30 16:39:21 bigbertha postfix/qmgr[16356]: 78861CCFF: removed Given that the remote mail server is returning a "250" status, why would I not get a successful DSN? The return code looks exactly the same as mail to a test yahoo account that I *did* get a successful DSN generated for: Nov 30 16:38:28 bigbertha postfix/cleanup[18162]: 17F73CCFF: warning: header Subject: test from c-98-197-129-225.hsd1.tx.comcast.net[98.197.129.225]; from=<rjo...@eggycrew.com> to=<redacted> proto=ESMTP helo=<[192.168.2.3]> Nov 30 16:38:28 bigbertha postfix/qmgr[16356]: 17F73CCFF: from=<rjo...@eggycrew.com>, size=785, nrcpt=1 (queue active) Nov 30 16:38:30 bigbertha postfix/smtp[18341]: 17F73CCFF: to=<redacted>, relay=mta5.am0.yahoodns.net[67.195.168.31]:25, delay=2.2, delays=0.16/0.01/0.28/1.7, dsn=2.0.0, status=sent (250 ok dirdel) Nov 30 16:38:30 bigbertha postfix/bounce[18342]: 17F73CCFF: sender delivery status notification: 3827D74091 Nov 30 16:38:30 bigbertha postfix/qmgr[16356]: 17F73CCFF: removed I have a feeling I am misunderstanding what communication takes places behind the scenes when a DSN is requested. If someone could shed some light on it for me, that'd be awesome :)