I am also having problems sending or forwarding emails on Windows Live Mail under Windows 8.1.
Was fine until 4 weeks ago. In bound messages are normal on 3 accounts
When I hit the send key the program freezes and I have to close it with task manager to continue.
Installed Mozilla Thunderbird which works fine so I presume there is nothing wrong with the accounts.
As I still prefer the Live Mail interface I would like to sort this
Advice please