Why does it say my account is "bouncing"?
If group messages sent to your email address are returned to Yahoo! Groups as undeliverable ("bouncing"), your Yahoo! Groups account may be temporarily disabled.
Messages can be returned for several reasons:

Your mailbox may be full -- try deleting messages from your Inbox.
Your ISP may have a backlog of email to process -- contact your ISP.
Your ISP may be blocking email from Yahoo! Groups -- contact your ISP.
In many cases, Yahoo! Groups can automatically reactivate your account once the delivery problem is solved. However, in some cases you will need to manually reactivate your account:
Visit your My Groups page.
Look for a bounce alert near the top of the page.
Click the Alert link to reactivate your account.