Comcast Servers on blacklists, causing delivery issues

Our comcast business email is experiencing trouble sending mail to customers with aol, yahoo and gmail addresses. The problem started in October.

All of our outgoing email seems to be routed through these three comcast smtp servers:

69.252.207.30

69.252.207.29

69.252.207.121

All three of these servers are on several server blacklists. I suspect this is the root cause of our business email not being delivered. Please do whatever is necessay to get these servers off the blacklists.