Microsoft Entourage: Error 17099

[stonedrama]

I'm using Office 2004: Microsoft Entourage. When I try to send mail, I get an error message that reads:
Relaying to <the email address> prohibited by administrator
Explanation
Email could not be sent
Account name (my account name)
Error 17099

My ISP is Earthlink, they confirmed this is not one of their error messages.

I haven't a clue...

Thnx

[bobw]

Go to Entourage > Preferences. Under "Mail & News Preferences", select
"Compose". Under "General", uncheck the option to "Automatically check
names when sending messages" and click OK.

[stonedrama]

This suggestion didn't work. The button you suggested to click off, was already clicked off. Any other suggestions?

[lscweb]

Not sure if your issues have been resolved, so I am just throwing somethings out here, as I don't use Earhtlink - have had too many issues with them for my clients residential & business. Anyway, is it possible that you need to have authentication turned on for you SMTP server? You did not mention if this email account is an Earthlink account or some other domain, anyway, another setting, is that many of the ISP's have started to block port 25 on email accounts that are not their own - so you can try to change this to an alternate port 587 for most email providers. Both of these settings are found under Entourage >> Account Settings >> your email account >> Account Settings Tab >> Sending Mail >> Click here for advance sending options >> Check Overide default SMTP Port (change to 587 from 25) also Check SMTP server requires Authentication and in most cases Use same settings as receiving mail server

[CatMom]

I tried both suggestions with no luck. I received this message with the last idea:

Authentication failed because Entourage doesn't support any of the available authentication methods.

I am trying to send from my Mac address book to a group and have already tried to reduce the group size to only 5 addresses so that did not work either.

Any other ideas?

Thanks,
Cat