What does the error message say?
i have no idea what 'Charter email' is, but after a quick search on google i see a few people say they had to switch on the authentication option for the SMTP server.
In Entourage open your account settings and click the button below you SMTP server box, for advance options. Tick the box that says SMTP server requires authentication and make sure the radial button if on for use same as incoming.
hope that helps?