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.