SMTP authentication issues with Outlook 2007 on Vista (Plesk, using POP3)
Some Outlook 2007 POP3 users have reported issues authenticating to our Plesk mail servers to send mail.
with an error: "This client does not support any of the authentication methods used by this server"
Here is a fix around this issue:
Display your account's outgoing mail (SMTP) settings in Outlook:
click on the Tools menu, then Account Settings
Select your email account, and under the Outgoing Server tab
leave My outgoing server (SMTP) Requires Authentication checked
check "Log on incoming mail server before sending mail."
This will allow you to authenticate with our servers.