HB - as everyone will tell you, AOL 'moves in mysterious ways'. This is a known issue and you will probably have to learn to live with it. I think they block ports at will to try to force you into AOL mail. I take it you are minimising AOL after logon and using OE, and I also assume you are only experiencing this problem on send?
I am using all my old addresses with it but I have to 'duck and weave' with AOL sometimes to get mail away. If it is of any interest I am shortly dumping it now my 12 mths are up and going to a cheaper b/band service. When they took away the 'bundled' travelling dial-up and started charging extra for it that was the last straw!