I don't know if you can keep the sbcglobal address, but if you go to this page
http://forums.att.com/t5/Email/keepi...s/td-p/2012943
they provide a chat link for people to migrate their att.net mail address to a free account when they leave at&t.
and this dsl forum link says you can keep it forever (a recent change)
http://www.dslreports.com/forum/r226...ter-DSL-cancel
They may offer the same for the sub domains or whatever they call them.