What would cause your email program to suddenly not send emails? I have Windows Mail and all of a sudden I cannot send emails although emails are received as usual. I have not changed anything at all on my computer. Just turned it on this morning as usual and when I tried to email my wife it wouldn't send and after a half minute or so I get an error message with some mumbo jumbo about SMTP protocols which again, I haven't changed. I tried sending test emails to other email addresses as well in case there was something going on with her email but they wouldn't send either.