We recently had a customer get a ISP change and on the same day were moving their DNS to Godaddy. A few weeks later they noticed a bunch of emails bouncing back with a lot of the email addresses being for Comcast. We weren’t sure if this was a Godaddy,DNS, Exchange, or ISP issue.
It turned out to be the ISP needed to a PTR (pointer record) to the IP address.
This link helped us know that the PTR record is set by the ISP.
Here are some of the other things we had tried.
- Adding the static IP to their SPF record.
- Adding a Reverse Zone Record in the exchange server.
- Turned off Spam Filtering in their email account
Let us know if this helped you…