Let me tell you our problem:
Our board 15 years online, and most of emails not working. Some people changed email address, some ... I dnt know, where are they.
For example - user visited board 3 or 4 yrs ago, but still receiving emails from board every day (he or she followed topic or forum). I think thats a wasting money for email sendings.
So, what you can recommend for this case?
Unfollow all users from all the board?
P.S. submit post working too slow, because board sending notifications to all followers 😞