The current topics under Business Internet don't include "Email".
Comcast support for email is terrible. The postmaster account is a black hole. You can send email but don't expect a reply. There is postmaster web page but no way to contact anyone except for the problem of IP blocking (RDBL). The postmaster web page has not been updated since 2014. The phone support will get you someone that doen't know what SMTP is, has no category appropriate for the problem so doesn't know how to report it and will refuse to escallate.
The online forum seems the only place where someone can be contacted with a clue that can also help get an issue resolved. So an Email topic might be helpful.