Hehe... I tried chevereto on PHP 7 on my virtual clone-site the other day..... looked good at first view but then couldn't show the images, functions not working...
Didn't investigate further, just stated the fact that there's a lot of work to be done....
I haven't had a single SMTP-fail since yesterday so now I feel you can close this thread, and maybe it would be of help to anyone experiencing the same problem.
The weird thing is still the fact that my wiki and wordpress that are running on the same server, same PHP & MYSQL haven't had any SMTP problems at all.