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Thanks for the report Ryan. There are two protocols for
accessing AIM: Ayttm uses TOC, while Gaim uses OSCAR by
default. May be TOC doesn't support @mac.com screennames ?
I'm not sure... It is planned to add support for OSCAR in
Ayttm, but I don't know when it will be completed. You might
want to try to build ayttm with --enable-oscar (and then add
a new account with OSCAR protocol). It might work but no
guarantee ;-)