I install an application, that it needed smtp information for sending mail, I provide smtp user, password and host for that application, but when it tried to send mail this error had occurred in the application:

"SMTPRecipientsRefused: {'ash.mavi@gmail.com': (550, '5.1.0 <bounce-14-res.users-5@aaslaam.com>: Sender address rejected: User unknown in virtual mailbox table')} ".

what should I do?

mail server log:

Apr 29 13:41:41 ns3 postfix/smtpd[30281]: connect from unknown[xx.xx.xx.xx]
Apr 29 13:41:41 ns3 postfix/smtpd[30281]: NOQUEUE: reject: RCPT from unknown[xx.xx.xx.xx]: 550 5.1.0 <bounce-15-res.users-5@aaslaam.com>: Sender address rejected: User unknown in virtual mailbox table; from=<bounce-15-res.users-5@aaslaam.com> to=<ash.mavi@gmail.com> proto=ESMTP helo=<ns1.webmart.com>

If you need to know more information, let me know.

  • Check your postfix logs, but thereis two spaces between "User" and "unknown", so there is no user provided to the MTA, and it reject your mail
    – Dom
    Apr 29, 2014 at 10:58
  • I placed server log corresponding to this error. Apr 29, 2014 at 11:46
  • Are you using SRS? Also, since the email is from your domain (possibly) but to an external domain (gmail) it's normal that you wouldn't allow relaying from ns1.webmart.com
    – NickW
    Apr 29, 2014 at 11:53
  • I don't know SRS, I simply install and configure postfix with installing iredmail. How can I found whether I using SRS or not? Apr 29, 2014 at 11:56
  • Don't worry about it. First, who is it sending that mail, second, is it in your network, third what are you trying to accomplish exactly?
    – NickW
    Apr 29, 2014 at 11:59

3 Answers 3


Postfix rejected unknown senders. Comment out one line in /etc/postfix/main.cf:

#smtpd_reject_unlisted_sender= yes

and your problem will be solved.

  • 1
    This is a serious security risk. If your machine somehow gets hacked, your machine can be turned into a SPAMbot... Nov 29, 2016 at 19:20

If using a file instead of a table, run sudo postmap /etc/postfix/virtual_mailbox_maps after ensuring the target address in in there.

  • Can you explain how this will solve the OP's problem, given that there's no indication that Postfix is configured to look in /etc/postfix/virtual_mailbox_maps?
    – womble
    Mar 31, 2020 at 21:25

Please check if the address where are you sending to is written correctly and there are no spelling errors,(space,dot, .etc).

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