Changed Host, no Notifications have been send since..

We are using MailPoet to send weekly notification messages of the last N post to about 650 subscribers.

We have changed host since 3 weeks, from SiteGround to Antagonist.

Since then, our notifications are not being send anymore. Still, there has not been an error message or anything that points towards any reason or solution.

Could you please help me to find out what happened?
Could it be that our account has been suspended?
If so: why didn’t we get a notification about that?

The page I need help with: [log in to see the link]