Hey everyone! I'm in a bit of a bind and could really use your advice. We recently switched our ISP from Comcast to Verizon FIOS and since then, we've been getting listed on Spamhaus almost daily. We've set up the rDNS for our mail server, which initially helped, but it hasn't solved the ongoing issue. Just yesterday, Spamhaus blocked us again, showing incorrect HELO information related to our IP. I've run checks on MXToolBox, and everything seems fine from my side, but I'm at a loss here. Is there something in our firewall, exchange settings, or DNS configurations that I might need to update? Any tips or suggestions would be greatly appreciated before my office turns into a mob with pitchforks!
4 Answers
Consider using this as a chance to push for a cloud email solution. Services like Google Workspaces or Microsoft 365 can simplify your email management and reduce headaches related to your own mail servers. Don't forget to make sure Verizon has your PTR records set correctly and that your SPF records are validated properly. You might want to check out https://www.mail-tester.com/ for a helpful tool.
Honestly, you should move your email IPs away from any ISP-provided addresses. Switching ISPs often means you lose your sending reputation, and as you’ve seen, it can be hard to regain. Looking into using a service like SendGrid or SES could really help maintain that reputation better.
I’ve heard about reputation issues being common after an ISP switch. Thanks for the advice on the sending services!
You should stop sending emails directly from your own network. Consider using anti-spam solutions that allow you to route your mail through a smart host like Exchange Online Protection. This can significantly help improve your sending reputation and avoid issues with Spamhaus.
Moving to a cloud-based email service is definitely the best long-term solution. It’s important for your sending IPs to have a clean reputation, which can take a while to establish, especially if you offer services like guest WiFi that users might abuse. Even if there's no guest WiFi, make sure your company network isn't compromised by any employees' personal devices.
We don’t have guest WiFi but I worry that personal devices on our network could be causing issues.
We’re off the list for now, but it’s only a matter of time before we get relisted. We’ve looked into cloud options, but some legacy software relies on our current setup. Cost is also a factor for us.