I've been having issues with WLM since December. I have a gmail account and run on Windows 8.1. I've been a part of other threads. I've tried some of the posted solutions, but have not resolved my issue.
I can receive emails. Some messages will send, but not if they have attachments.
I don't get an error. I get a message that says, "The message could not be sent. A problem has occurred. Try again. "