Ajax errors when sending test email

HI Team =)

Wondering if anyone can help me with this? I configured Postman SMTP correctly and created an APi instance and configured that correctly, and authorized javascript locations and all that jazz – and e.v.e.r.y.t.h.i.n.g. was working fine and dandy!

Now I see a massive drop in user registrations and I look straight to the email plugin. Prior to that I had attempted to register a test user via the front end and the operation times out (presumably because the email system isn’t working)

I have checked all the logs and I don’t know where to start – what I do know is that when sending a test email message I get the following error

“AJAX Error – An unexpected error occurred:”

D:

halp? Where do I start with this?