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Nigel Metheringham edited this page Nov 29, 2012 · 2 revisions



Exim is logging the unknown SMTP command XXXX from my client hosts, and they are unable to authenticate.


This is a sign of a Cisco PIX firewall getting in the way. It does not support ESMTP, and turns EHLO commands into XXXX. You should configure the Pix to leave SMTP alone; see `../Q0053`_ for how to do this.