I'm having the same problems and don't know what to do so would like some help too. I've just installed a new pc and have windows 8.1 which I am not getting on well with and don't like the email system as worked very slow  so downloaded windows live mail 2012 and really like the setup of this as similar to what I am used to when I had windows vista. I have set up all my email accounts (8 in total sky and yahoo mail) and I receive emails with no problem but unable to send any emails and get the below message

The message could not be sent because the server rejected the sender's email address. The sender's email address was ********** (deleted my email address)'.

Subject 'Swimming Lessons'
Server Error: 530
Server Response: 530 5.7.1 Authentication required
Server: 'smtp.tools.sky.com'
Windows Live Mail Error ID: 0x800CCC78
Protocol: SMTP
Port: 465
Secure(SSL): Yes

Please can you help resolve this problem and is windows live mail 2012 the best email client to use with this view.

Regards and looking forward to your reply

Two identical questions merged and the duplicate post deleted