Question : Cannot email bellsouth.net addresses.

On a network that I manage, most users are unable to email bellsouth.net accounts.  The server has Windows 2003, and the email client is Outlook.  I am able to log in to the server as the administrator and email certain Bellsouth.net accounts, but not other accounts from Bellsouth.net.  Other users are not able to email any bellsouth.net accounts.

Answer : Cannot email bellsouth.net addresses.

make sure you have a Reverse DNS Entry with your ISP setup.  Some domains will not accept e-mail from mail servers unless it can perform a Reverse DNS lookup on the sender.