All Barracuda Spam Firewalls, all firmware versions.
If your mail server is configured to reject mail addressed to invalid recipients, the Email Security Gateway will automatically use your mail server to determine which recipients are invalid to block them sooner (unless some other form of recipient verification has been enabled). This is called SMTP verification. However, if your mail server is configured to do this and the Email Security Gateway is not recognizing invalid recipients, your mail server may be configured to reject mail from any postmaster address, which the Email Security Gateway uses in its recipient verification tests.
If you suspect this may be happening, you can change the from address the Email Security Gateway uses in its recipient verification tests on the Advanced -> Expert Variables page. Here, you can change the Recipient Verification From Address option to something other than email@example.com.
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