ATT email IMAP configuration in Outlook 2010 issue !!

Hello All

Can any one suggest the solution of my following issue  ?

Issue:  not able to configure ATT email (imap) in the Outlook 2010 and get error

Error:  Log on to incoming mail server (imap): server refused connection

          Sent TEST email: outlook can not sent smtp message to server

What I did to configure:

Open the outlook -> add new email -> user id / Password -> incoming mail server setting (imap.mail.att.net) and outgoing mail server settings -> smtp.mail.att.net -> set for IMAP -> Click: NEXT

Getting error messsage as mentioned above.

I checked over internet my email is working fine with ID and PASS word I am using. I don't know why I am refused by incoming and outgoing mail server ?

Can any one suggest the solution ?

Thanks -  Indra