Mailing List Message #106928
From: DUDLEY Paul <>
Subject: 550 server without authentication error
Date: Wed, 15 Aug 2018 04:32:04 +0000
To: CommuniGate Pro Discussions <>

We are running CommuniGate Pro v6.2.0 on a Red Hat linux server. When we try to send emails to a specific external address, their mail system replies with the following delivery failure:


Failed to deliver to ''

SMTP module(domain reports:

host says:

550 server without authentication.


At this point in time this is the only external email domain that we are sending to which is reporting this problem.

Are there any settings I can check on our CommuniGate Pro server?




Paul Dudley



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