If you forward your mail and click the Report as Spam button you are blocking your own mail server.

Instead of blaming your provider for the problem perhaps just do a search. You will find out that now Comcast has gone right to the top with lame email servers they are only matched by AOL.

Due to strict spam policies with Comcast and AOL and blacklisting our mail servers as a result of clients forwarding their email, we have been forced to change our policy with regard to email.

We have been left with no other course of action than to block forwarding to these domains server wide. Mail will no longer be allowed to be forwarded to any ISP that will easily blacklist a server with no way for the end user to whitelist an email address or domain name. This is to prevent issues with companies like AOL or ComCast blacklisting our servers without cause.