SMTP issues. Error 451.

[DrJohnZoidberg]

I've been looking around now for a solution to my problem but haven't really found a definitive answer yet.

Does anybody know why I would receive the following error:

451-host lookup did not complete 451 Could not complete sender verify (in reply to RCPT TO command)

Mail is getting relayed through the IS SMTP server (using smtp.openweb.co.za at the moment).

Weird thing is that some mails have gone through but the majority are not, like this:

Oct 22 14:40:49 server-01 postfix/smtp[13659]: 90754226233: to=<[email protected]>, relay=smtp.openweb.co.za[196.26.208.200]:25, delay=3, delays=0.05/0/0.61/2.3, dsn=2.0.0, status=sent (250 OK id=1TQHIf-000FEe-26)
Oct 22 14:43:10 server-01 postfix/smtp[14061]: 633202261BA: to=<[email protected]>, relay=smtp.openweb.co.za[196.26.208.200]:25, delay=109377, delays=109370/0.01/0.72/6.4, dsn=4.0.0, status=deferred (host smtp.openweb.co.za[196.26.208.200] said: 451-host lookup did not complete 451 Could not complete sender verify (in reply to RCPT TO command))

How do I fix this? We have 22 mails in the queue now that haven't sent yet.

Thanks in advance.

 

[Murlin]

Looks like you hostname of the server does not resolve to anything. Eg : mail.test.com is the server hostname. The world can see this as a record/it resolves

 

[DrJohnZoidberg]

Looks like you hostname of the server does not resolve to anything. Eg : mail.test.com is the server hostname. The world can see this as a record/it resolves

Yes, you're right. Just found out one of our domains just disappeared :erm:


Thanks for taking a look.

 

[guest2013-1]

fyi, googling that error as if (451 could not complete sender verify) shows the answer in the first post. Glad Murlin could help