>Can it be because your ISP changed some settings regarding mail relay? I >had experienced (and still experiencing) a similar problem after the >sysop to my ISP (i.e. the University) had changed. He closed the main >mail server to relay and unfortunately did not know how to allow certain >IPs. So, after waiting for months for a solution, I decided to run my >own mail server on another machine and am looking into installing >Stalker Internet Mail Server.
Lots of ISP are stopping the relaying of mail. Unfortunately TF does not send mail like EIMS and give you the option to go via a host or not.
