With many types of business email accounts, your computer connects to a machine called the Simple Mail Transfer Protocol server when you send messages. If you have difficulty sending messages, there ...

Not much help with Entourage, but Mail.app asks if you want to try a different smtp when it can't send... a very nice feature that I haven't seen elsewhere.

Some Outlook users have reported that they are unable to send email from the app as when doing the same, they receive Error 503 stating that the Valid RCPT command ...