I had a short-lived episode where one of my customers was spamming. I was able to shut it down quickly, but not quick enough to avoid getting SMTP blacklisted by RCN. The response from their mail servers is:
SMTP error from remote mail server after initial connection:
host mx.lnh.mail.rcn.net [188.8.131.52]: 554 mx05.lnh.mail.rcn.net
No information there on what blacklist system they use, or how to get de-listed. Nothing that I can find on RCN's web site. Mail to postmaster is ignored. Mail to support is ignored. Can't get past 1st-level support over the phone. I'm stuck. Blacklisted and can't get off.
Anyone dealt with this with RCN before? Any tips?