Can someone from Joomlapolis please let us know where this issue stands as far and upcoming releases are concerned? Would it be possible to just give us a config option that will allow us to completely turn-off the AJAX check - front-end and back-end? It is such an intrusive feature, and more than half of the valid email addresses I use come back with an error due to the mail server configuration. So where is the benefit to me?
I would MUCH rather see you implement an email verification field, forcing the user to re-type their email address, rather than this AJAX checker.
Just my opinion, of course...