Philippe,  I get a _ton_ of spam from the French <.fr> domain, so
much so that I have recently considered blacklisting the entire domain.
The Brazil domain <.br> is also under consideration.  ATT's response is
fairly radical but they must believe, as I do, that the only effective
way to stop spam is at the source.  All the ISPs have terms of use
which preclude sending spam.  ATT's decision is intended to get the ISP
to _enforce_ those conditions of use.

Unfortunately many other customers of those ISPs suffer unfairly.
I would suggest:

1. Complain to your ISP that they do not do enough to prevent spammers.

2. Get a gmail (Google email) account.

Gmail has its own drawbacks but it should solve your trouble with ATT.
Good luck.

Regards,
Phil Duclos