OK, I just got off the phone with Comcast after a joyful 25 min. on hold, interspersed with 30 second conversations and being transferred around in circles.
This is what I have gleaned so far-
IF Comcast has blacklisted the URL, it is because a virus was detected in a message originating from that URL. The entire URL will remain blacklisted until such time as the URL owner contacts Comcast, and they work things out.
I say IF, because after talking with 3 persons at Comcast regarding this issue, I was given a blacklist specific 800 # to call to confirm the blacklist. If I get a chance, I will try it later, but here it is if anyone else wants to give it try-
800-871-6298 Option 2