Hey everyone, I recently migrated to a new ISP and updated our edge network. After configuring the firewall and NAT rules, our on-premise Exchange Server was supposed to relay emails to Exchange Online without issues. We even updated the IP in the Exchange Online Admin Center and whitelisted it in the connector policy. Email migrations are working fine, but we hit a snag with our SMTP server used for in-house scanners and some custom apps. Now, every time we try to send an email, we get blocked by Spamhaus with a message saying our IP is listed. We've already requested removal from Spamhaus, and they show no issues with our static IP. Is there anything else we need to check, or are we just being impatient? Any advice would be appreciated, thanks!
4 Answers
I dealt with a similar situation a while back. Just a heads-up, Spamhaus has two different blacklists. One tracks real-time activity while the other marks 'end-user IPs' that shouldn’t normally be sending mail. Make sure you're off both lists to avoid issues!
Man, dealing with EOP can be a real headache. I've seen similar issues where Microsoft enforces email authentication even on hybrid setups. Try ensuring you've added your hybrid public IPs to the enhanced filtering for connectors. It might make a difference. Even if you’ve safelisted it, EOP can be stubborn. Just keep at it!
Hey! I run a competitive service to Spamhaus, so I can tell you there's definitely some nuance in those lists. Make sure your SMTP setup isn’t exposed to the world; if you’ve set things up improperly, you could open yourself up to issues like being flagged as an open relay. If the Spamhaus removal doesn’t work in your favor, let me know the IP, and I'll take a closer look!
Hang tight, it can take a while for everything to clear up. Just make sure your reverse DNS is properly set up with the new ISP since that can affect deliverability too. Keep an eye on it; it might just need a bit of time to refresh!
I appreciate your insight! I ran tests again, and everything still fails with the same error. I’m not sure how else to verify with Spamhaus since their lookup says we’re clean. I’ve done all the right tweaks; it’s just frustrating. Thanks for the offer! I might just reach out soon.