Blacklisted

Maybe try rephrasing your question. Your router does not provide a public ip address. Comcast provides the public ip address to your router. Your router provides private ip addresses to the devices on your LAN. These ip addresses can not be "blacklisted".

Describe your problem in detail providing context rather than jumping to the conclusion that some ip address is "blacklisted".

cstraub34 wrote:

Comcast blocked third party IP addresses in a sever upgrade. You need to contact Comcast to have the issues corrected.

It is still not clear what the issue is. Are you saying Comcast does not relay email from non-comcast ip addresses? If so, most ISPs do the same thing as spam prevention. Please provide details. How does this relate to Apple or Apple products?

cstraub34 wrote:

Comcast email account used in Apple email some have been blacklisted. Many others are have the same problems and after dealing with multi support group trying to pin point the issue. I was able to find out that Comcast no longer support third party programs. I only have email with Comcast and not the service.

Are you saying that Comcast users can not use Outlook, Apple Mail, Thunderbird, etc. email clients? I find that hard to believe.

Here are their instructions for setting up third party email clients for use with Comcast email servers:

https://www.xfinity.com/support/articles/email-client-programs-with-xfinity-email