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Can a Barracuda SF 300 reject mail based on DNS?

Specifically can it respond with a 4XX code for mail claiming to be from a domain without a valid MX or A record (similar to postfix's smtpd_sender_restrictions = reject_unknown_sender_domain).

If so, how do I set it? (I realize it's probably something simple I've overlooked.)

The barracuda can resolve using its configured name servers.
The name servers can correctly resolve external domains.

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If you have a support contract, their technical support is pretty good. – Nixphoe Nov 17 '11 at 23:38

Yes, sorta. Assuming you have a recent firmware edition, navigating to Block/Accept -> Reverse DNS, you have the following options:

enter image description here

Specific error or bounce-back messages can be configured in Advanced -> Bounce/NDR Settings. You may also want to look at the Deep Header Scan option.

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up vote 1 down vote accepted


Apparently barracuda previously had this option, but removed it some time ago do to a DOS vulnerability it exposed their system to. (I believe related to a domain with a large number of MX records.)

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