i think this is solution to error 999 yahoo mail
hii friends
i think there is just a small settings change to solve error *** yahoo mail problem
even i encountered the same problem and couldnot access my account for seven days.
thanx god it is solved now.
i might be able to provide you solutions to solve it
mail me at [email]sachin.bhayana@**********[/email]
Workaround to "error 999"
Yay! I've finally come up with a pretty good workaround for this problem!
I have four Yahoo mail accounts and also use ePrompter to automatically check them (no, unfortunately, it doesn't work real well with Yahoo), and I get the "error ***" message on one account or another almost every day. Here's a workaround that seems to give access to the "unavailable" mail accounts pretty consistently; it requires the use of Yahoo! Messenger, so you'll need to have it installed on the computer from which you want to do this.
Log into Yahoo! Messenger using the account name you want to access. Select "Yahoo! Account Info" from the Messenger menu. It should open a browser window, ask you for the password on the account, then show you your account information. Click "Finished" in the account info window. Then click the "Mail" link in the upper left hand corner.
This should give you access to the account most of the time. Good luck!