2 days ago my email notification stopped working. I'm assuming it had something to do with my server. When I came here to find a solution it looked like I wasn't the only one with a problem. Most of the posts had no answer.
Here's what worked for me:
That plugin, and I changed my email address to be server based instead of Gmail. Make sure once you've activated the plugin that you go into the options to turn it on, and make sure the specifications are correct.
It's working like a charm now.