I can see that Thomas has your ticket in his queue, meaning that he is working on it
I can also see that you probably have way too many emails configured to be sent in short period of time. Your configuration shows that you are trying to send 1500 emails every minute
It would mean that you would send 25 emails per second. That is a huge resource eater and no wonder your server crashed
I don't know what kind of server do you have, but I am almost 100% sure that your server can't handle so many emails per second. I have seen servers that can do it, but those servers were strictly email servers and nothing else and on top of that, they were highly optimized for the job
Try to lower your email sending configuration to some more optimistic values