Hi, Noel thanks for the analytic answer! I was thinking the exact same thing, the receiving server is not very friendly. Just in case I'm missing something this is my postconf -n <http://pastebin.com/tsM7YS92>
Thank you, Chris On 11/05/2015 09:34 μμ, Noel Jones wrote: > On 5/11/2015 10:48 AM, Specktator wrote: >> >> >> Hi, >> >> I'm more or less new to postmastering and I'm facing some errors >> displayed below. >> >> I reached the fellow postmaster of the receiving server and he said >> that recipient address verification could cause the problem and >> attached for me his postfix error log. > This doesn't necessarily have anything to do with address verification. > >>> May 6 22:39:17 receivingmailserver postfix/smtpd[37426]: too many >>> errors after RCPT from mail.example.com[4.2.3.1] > The sender exceeded the postfix smtpd_hard_error_limit. > http://www.postfix.org/postconf.5.html#smtpd_hard_error_limit > > Prior log entries show what those errors are. Typically, this is > from sending mail to unknown recipients. > >> Since I'm not familiar with recipient address verification, I've >> read the docs though, but can't clearly understand / decide if the >> error comes from recipient verification probing or something else. >> Is it good to have it or it should be disabled it? > Did you configure postfix to send verification probes to remote > systems? You shouldn't do that, but it's not clear that's the > problem here. > > >> Which is the best practice? >> >>> >>> Here's my log: >>> >>> May 6 22:19:16 mail postfix/smtp[3857]: C3433140E0F: host >>> mail.example.com[] said: 450 4.2.0 <us...@med.example.com>: >>> Recipient address rejected: Greylisted, see >>> http://postgrey.schweikert.ch/help/med.example.com.html (in reply >>> to RCPT TO command) >>> May 6 22:19:16 mail postfix/smtp[3857]: C3433140E0F: host >>> mail.example.com[1.2.3.4] said: 421 4.7.0 mail.example.com Error: >>> too many errors (in reply to RCPT TO command) > You send mail to ONE recipient, the other server rejects the > recipient for greylisting. > > Then the other server hangs up. Apparently the other server has set > smtpd_hard_error_limit = 1. > >>> May 6 22:19:16 mail postfix/smtp[3857]: C3433140E0F: lost >>> connection with mail.example.com[1.2.3.4] while sending DATA command >>> May 6 22:39:17 mail postfix/smtp[4443]: C3433140E0F: >>> to=<us...@med.example.com>, relay=mail.example.com[1.2.3.4]:25, >>> delay=3983, delays=3980/0.03/2/0.41, dsn=4.2.0, status=deferred >>> (host mail.example.com[1.2.3.4] said: 450 4.2.0 >>> <us...@med.example.com>: Recipient address rejected: Greylisted, >>> see http://postgrey.schweikert.ch/help/med.example.com.html (in >>> reply to RCPT TO command)) > and another greylisted recipient... > > My analysis... > This is a result of recipient system using an unreasonably low hard > error limit combined with greylisting, possibly exacerbated by your > system sending to multiple recipients at the same time. > > The mail should go through eventually after the greylisting has > cleared with no further action on your part. > > This doesn't seem to be a config error on your system. > > > > > -- Noel Jones >
