Hi Nikola, It looks like a stupid thing to say but as a WordPress developer, the emails failing to send had caused me lose so much time for a client. I have been trying to find why this was happening for 2 days now. Apparently, I changed the Email field to Email Address as per client's request. I saw the Error Log and it kept on saying no receipients email found. So, I changed back from Email Address to Email and it worked magically. 

So, my question is isn't that not a good thing to allow changing Email if you are hardcoding to find Email? If not, maybe you can restrict the name of that field to email and only change the label to anything user wants. This will save a lot of headaches. I saw several threads about this as well. Please fix this bug. :)   Thanks,
Chandra