Problem sending mail in outlook

[collusion]

One of my clients recently switched his domain from godaddy to my server. He had a problem sending email through outlook but he could recieve it fine. He could also log in to webmail and send and recieve. I figured out that my server was set to use port 26 so I had him change his from 25 to 26 and he tested it and it worked. About an hour later it stopped working but his settings remained in tact so I do not know what is wrong this time. Is this a resolving issue? and will it fix itself? I had the problem before on one of my domains but it fixed itself by the next day.

[collusion]

It has been fixed. aparently Outlook requires you to put + instead of @ in your email address as your login name. So that fixed one of their computers. The other turned out to be a firewall preventing outgoing smtp accesss. Outlook express uses the @ by the way..