I, like many people have a Yahoo! Mail account. However, I like many other people do not use Y! Mail anymore as I have Gmail now. Y! was good to me for a good 8 years though. New AJAX interface for managing email was just too slow, and after 8 years I get A LOT of email.
yes it has different servers in various countries. i dont think i has effects on other accounts using servers for example in asia.