Blacklists
I've recently been having issues sending mail to various domains from NeoPhi since it is currently on an RCN static IP. It seems various email blacklist sites have started adding cable modem IPs. RCN technical support was no help in trying to resolve the issues. In the end I decided to use RCN's mail server as my outgoing relay in the hopes that at least that RCN machine isn't blacklisted.