This solution applies to all Barracuda Spam Firewalls, all firmware versions.
When an email is blocked for reason of Client (as displayed on the Basic > Message Log page), it is because the Barracuda has been configured to block that specific IP address. You can check these settings by going to Block/Accept > IP Block/Accept page and looking at all of the IP ranges currently being blocked by the Barracuda Spam Firewall. If a netmask of 0.0.0.0 has been entered for any entry, this means the Barracuda will block every possible sender, so use care when specifying the IP ranges.
Likewise, when an email is whitelisted for reason of Client (as displayed on the Basic > Message Log page), it is because the Barracuda has been configured to allow that specific IP address in the same way on the Block/Accept > IP Block/Accept page. If the Barracuda Spam Firewall is allowing too many messages for this reason, it is possible that too broad of a netmask has been specified which has resulted in whitelisting some or all incoming emails. Also, if there is another mail transfer agent in front of the Barracuda Spam Firewall (like an SMTP proxy server), you may want to make sure that server's IP address has not been accidentally whitelisted.
You cannot read any emails blocked for reason of 'Client' because they were blocked at time of SMTP transmission, there fore the email was not written to disk to be redelivered later.
If some or all of your incoming mail first travels through an SMTP proxy server, relay server, or mail server before reaching the Barracuda Spam Firewall, you should exempt the IP address of that mail server without whitelisting it. On firmware versions 3.5.10.027 and above, the easiest way to do this is to list it as a Trusted Forwarder. For instructions and information about this feature, please see Solution #00003211.
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