Unable to send mail, authentication not enabled

I'm stuck with the following error, after I've triple-checked with the webhost that I've got the external smtp mail settings right. Apparently, C5 requires authentication, where the webserver does not. Just putting the password does not work, and a missing password apparently does not turn it off either.

Here's the log description:
Mail Exception Occurred. Unable to send mail: 503 5.5.1 Error: authentication not enabled

Any clues?

View Replies:
heikonolen replied on at Permalink Reply
Just got the php mailer to work using an email work around from the webhost, but it would still be great to make the external smtp work...
Mnkras replied on at Permalink Reply
smtp requires authentication, otherwise anyone could send mail as you