I’ve got a small forum, less than 3k users.
And at sparkpost report:
Of course SparkPost denied me the “sending” emails, so no new user activations are sending now and I must “pay” if I need fix this problem now :’(
At the moment I decided to disable the summary emails, and try to decrease any outgoing email from the forum., To see if I can reduce emails.
I detected this problem after updating latest version, I don’t know, maybe it’s coincidence.