The message could not be sent: bigpond.com server response: 550 5.1.0 Authentication Required

Hi,

I have just downloaded your WL update to 12 from WL11, it will now not send messages, they are stuck in the Outbox, yes, I have tried all the above without  fix, see error below:

The message could not be sent because the server rejected the sender's email address. The sender's email address was '*** Email address is removed for privacy ***'.

Subject 'Test'
Server Error: 550
Server Response: 550 5.1.0 Authentication Required
Server: 'mail.bigpond.com'
Windows Live Mail Error ID: 0x800CCC78
Protocol: SMTP
Port: 25
Secure(SSL): No

I tried to send email to myself, obviously there should not be any issue with this, I can send emails on my smart phone also, so definitely not email adress.

Please help.

Phill

Split from an unrelated thread