All Email Security Gateways, all firmware versions.
If the Email Security Gateway and the mail server are not experiencing an IP address conflict, it is possible they have the same hostname. On the Basic > IP Configuration page of the Barracuda's web interface, at the bottom, if the Default Hostname and Default Domain configurations are the same as those of the mail server, they will not be able to communicate properly. To fix this, simply change the Default Hostname field to something unique (like barracuda).
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