Opera

If you get the error message "SMTP authentication not supported by server" when trying to send e-mail, the cause could be that you have set up Opera Mail, Opera's built-in e-mail client, to send a username and password to authenticate with the server when sending mail, but the server does not support it.

To fix this problem, remove the username and password set up for the SMTP server, following the steps below:

1. Go to Tools > Mail and Chat Accounts....
2. Select the account you are having problems with and click "Edit...".
3. Click the Servers tab in the account properties dialog and remove the username and password entered under "Outgoing SMTP server"
4. Click "OK" to confirm the changes and close the account properties dialog.