Late on 3/20/2006, Frontier imposed new limits on email addressees. This was noticed by sending an email with many addressees and getting a "452" error - too many recipients " from the mail server.
After many phone calls and email exchanges, I was told that they did place new limits on outgoing emails because other ISPs have incoming limits and were rejecting emails from Frontier. However, several superviors told me that they either did not know what the limits were or were not allowed to tell me.
In the end, after escalation of the matter to the FCC and to Citizens Communications HQ in Connecticut, they finally gave me the current limits.
The limits are:
No more than 50 addressees on a single email
No more than 20 different domains (@xxxxxx) in a single email