Can a Barracuda Spam Filter 300 reject mail based on DNS?
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.
Solution 1:
Yes, sorta. Assuming you have a recent firmware edition, navigating to Block/Accept -> Reverse DNS
, you have the following options:
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.
Solution 2:
No.
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.)