Currently Being ModeratedSep 12, 2011 5:22 PM (in response to originale)
You don't really give us much to go on. Check and double-check your settings. Also review the information in the Connection Doctor (Window menu) which will tell you why the account isn't working.
Currently Being ModeratedSep 12, 2011 7:13 PM (in response to originale)
Basic solution, but one that's worked for me at times: Did you try Mailbox > Online Status > Take "account name in question" online?