Outlook Error when sending SBC Yahoo Email?

Two days ago, when i send email for SBC from outlook I am getting an error message 0X800cc0e. It says that it timed out and to contact system administrator. I called SBC tech support and they said it was becuase of my anti virus. I have an old computer with no antivirus and outlook and tried to send and got an error message also. Receiving is fine. Anyone have any idea what is happening. I think it's SBC, anyone have any input?