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.
https://community.spiceworks.com/topic/1212792-ptr-record-in-godaddy-not-working
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…