On 12.4.2012 13:29, Prabhpal S. Mavi wrote: > Dear All Greetings, > > i am admin for ISP two years now, relay emails for more than 300 companies > (CentOS/Postfix). Relaying more than 10,000 messages every hours > successfully. no one has ever compliant for non delivery. but i cannot > relay to this domain. The servers responsible for accepting messages are > rejecting. i have given the whole log for experts to monitor. > > it is something out of control, because it is not my problem. Our server > has all record created (A,MX,PTR,SPF etc). i have three relay hosts fully > functional. destination server is not accepting from any relay host. > > can anyone try from his server and see if it is deliverable to > ray at tata-nigeria.com > > Thanks / Regards > Prabhpal S. Mavi > > Apr 12 11:06:00 titan postfix/qmgr[11860]: C3C142E4012: > from=<****@digital-infotech.net>, size=1391, nrcpt=1 (queue active) > Apr 12 11:06:02 titan postfix/smtp[12039]: C3C142E4012: host > mx2.servershost.net[205.234.223.160] said: 450 4.1.7 > <****@digital-infotech.net>: Sender address rejected: unverified address: > host mail.digital-infotech.net[41.211.25.193] said: 450 4.7.1 Client host > rejected: cannot find your hostname, [205.234.223.198] (in reply to RCPT > TO command) (in reply to RCPT TO command) > Apr 12 11:06:03 titan postfix/smtp[12039]: C3C142E4012: > to=<ray at tata-nigeria.com>, relay=mx3.servershost.net[66.225.214.101]:25, > delay=1381, delays=1377/0.03/3.4/0.31, dsn=4.1.7, status=deferred (host > mx3.servershost.net[66.225.214.101] said: 450 4.1.7 > <****@digital-infotech.net>: Sender address rejected: unverified address: > host mail.digital-infotech.net[41.211.25.193] said: 450 4.7.1 Client host > rejected: cannot find your hostname, [205.234.223.198] (in reply to RCPT > TO command) (in reply to RCPT TO command)) > > Thanks / Regards > Prabhpal S. Mavi I think the destination server is trying a callback verification http://en.wikipedia.org/wiki/Callback_verification but that fails because your server is doing checks as described in http://en.wikipedia.org/wiki/FCrDNS $ host 205.234.223.198 198.223.234.205.in-addr.arpa domain name pointer mx4.servershost.net. $ host mx4.servershost.net. mx4.servershost.net has address 66.225.237.241 -- Kind Regards, Markus Falb -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 307 bytes Desc: OpenPGP digital signature URL: <http://lists.centos.org/pipermail/centos/attachments/20120412/8b9cb2ce/attachment-0004.sig>