I'm having the same problems as many others - I try to track and / or self-destruct emails in a conversation, and the screen says "mxHero Success!", but they stay in my drafts folder.  I don't know if they're sending or not, but I suspect they are not.  

I just checked to see if anything had changed, and I see it has actually deleted my draft that I had tried to send, which was a long email, sooooo yeahhhhhh now I'm quite annoyed.

I'm using a gmail address.  It seemed to be around the time of the Google Drive integration - but I use Google Drive and Gmail every day, and not run into problems before, so it makes sense it's with mxHero.  Sorry :/  

Love the product (and have been using it since the beginning of the year), but it has become too unreliable.  I'll wait a week or two before I do my write-up, to give a chance to fix the problem.  

Thanks :)