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
