I would like for IPS to hold the same options as other forums do and that is to supply a batch size on how many email notifications should be sent at once.
This size is configurable for bulk mails, but I would like to see it as a general setting.

The hosting provider that houses our forum (and we have a long contract with them) has a slow phpMailer / SMTP response.
This resulted in a very slow response when replying to topics (verified by Support). So for now I have disabled the email notifications altogether.
On the old forum (phpBB) I had a way to send emails in burst (i.e. 20 at once).

Maybe - if supported enough by others - this can make it to a new release?

If you're worried about speed. Why not setup a free account at Sparkpost? 50k daily, 100k monthly. What I've seen, works great. Wouldn't have to worry about hosts phpmail problems.

The problem I run into is Microsoft mail providers. If you send too many emails out in one batch and hit too many hotmail.com, msn.com etc. You get blacklisted as a spammer. The software needs a limit to how many it sends in a batch. I've quit with emailing newsletters because it just a fricking pain in the tail to fight email providers everything they decide to blacklist my domain.

As of 4.2.7, there is a new constant 'NOTIFICATIONS_PER_BATCH' which controls this.

Thanks Matt!!