Ubuntu – How to fix postfix: Sender address rejected: need fully-qualified address (in reply to RCPT TO command))

postfixUbuntu

I've installed dovecot, postfix and roundcube on an ubuntu 12.04 box.
The system is basically working – i.e it is able to send/receive mails to/from other domains.

However, some domains cause the following error message in /var/log/mail.log

Jul 15 01:59:21 one postfix/smtp[2019]: 0D0399C025F: to=<someone@destdomain.com>,
      relay=sm01.destdomain.com[x.x.x.x]:25, delay=0.56, delays=0.4/0/0.06/0.1,
      dsn=5.5.2, status=bounced (host sm01.destdomain.com[x.x.x.x] said:
      504 5.5.2 <contact@localhost>: Sender address rejected: need
      fully-qualified address (in reply to RCPT TO command))

Do you have any idea what's wrong here? I.e. How to force postfix to use "contact@mydomain.com" instead of "contact@localhost" when connecting to another mail server?

Any hints are appreciated.

Best Answer

$mydomain is used as a default value for many other configuration parameters, but it does not set the sender domain.

Take a look to the $myorigin parameter in /etc/postfix/main.cf

It specifies the domain that appears in mail that is posted on this machine. The default is to use the local machine name, $myhostname, which defaults to the name of the machine.

For more information, see Postfix basic configuration README

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