I have tried to sort this myself for months. Windows Live stand alone email on Windows 7 OS. 
A few months ago suddenly the SMTP stopped working. I have POP3 email provided by the people who provide my website. Simplewebhosting. I have all the settings from their website. 
Tried every premutation even tried IMAP. 
Had a break through today and I am now stumped. 
SMTP works if I email my own email address however it will not send to any others tried gmail hotmail icloud etc emailed lots of friends not one emails is going. 
An unknown error 

Windows Live Mail Error ID 0x800CCC0B

protocol SMTP

Port 25 

Secure SSL No

However i can send emails to myself. 
i have 2 email addresses and can send from both to myself. 

any other ports or setting i cant even send to myself. 

Thank you Lesley 

Edit

i checked the source of the sent messaage and it was delivered using LMTP server20.simplewebserver.co.uk esmtpsa 

I had called simplewebserver a few times and they says it is not their end. 
thank you 

Lesley