Nothing has recently changed on my end, but as of this morning, any attempt to send to my @0sg.net addresses (including "shielded" replies) are getting kicked back from gourmet7
host gourmet7.spamgourmet.com[216.75.62.102]
said: 550-X-Host-Lookup-Failed: Reverse DNS lookup does not match for
my.smarthost.ip.addr 550 (deferred) (in reply to MAIL FROM command)
The smarthost does have a properly set up reverse DNS/PTR/DKIM/DMARC/etc.., though, and has been working just fine for ages. It's not having issues with other mailservers using reverse-lookup checking (including my incoming smtp server).
Did something change?