GTE recently updated their email system. A reader found a problem with the update if you use Emailer 2.x: "To send mail, your 'email account' entry should be set up as <Account Name>@gte.net but to receive mail you have to change it to <Account Name>@mail.gte.net. To work-around this problem I configured 2 GTE accounts within Claris Emailer, GTE[get] and GTE[send], each one configured appropriately to get or receive mail."
I use GTE and can confirm this. When I try to send email under the "mail.gte.net" account name (which had worked fine previously both for sending and getting email), I now get an error that says: "SMTP server error "550... Relaying Denied." If I change the account name to "gte.net," the mail sends successfully. The two account set-up works okay for manually sending mail. However, if you have an automatic schedule to get/send mail, with both accounts included, the log will still record an error as it attempts to get mail from the "send only" account.
GTE confirms this problem and says it seems to be restricted to Emailer. Eudora works fine. They are investigating this further, but expect that a solution will need to come from Claris.