550-Callout verification failed: 550 550 5.1.1 User unknown

Discussion in 'General' started by ikrudolf, Oct 16, 2015.

  1. ikrudolf

    ikrudolf Member

    I have some error messages when sending mails to some addresses:
    550-Callout verification failed: 550 550 5.1.1 User unknown (in reply to RCPT TO command)

    Can anybody tell me what to do?
     
  2. victortruica

    victortruica New Member

    To which addresses are you trying to send - as in provider ? Microsoft is known to be problematic.
    What is the full output of the log entry in /var/log/mail log when you're sending these emails ?
    Looks like your destination address does not exist or its conflicting somehow with the spam filters on the receiving end. That, or something wrong with your headers ?
     

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