Throttling is presumably because you’re sending SMTP outbound directly - sites typically use third party SMTP services that won’t get throttled, to get around this, I believe.
(Throttling’s actually not the problem, it’s where the mails get outright rejected because of rate limits, for throttling your local SMTP service should be requeuing)
Yup - we’ve got the options in place for a more robust solution, separating transactional and bulk emails - bottom line is, by the time we get to the stage where we can afford a sysadmin, we’ll be good to go with whatever flexibility is possible - but while we’re muddling through without the necessary skillset, I’m always going to play on the cautious side of things…
This site isn’t doing SMTP directly; it’s using a third-party service. But I couldn’t possibly speak for the old site as it’s not something I’ve really been involved with. It is however a hosted service so I imagine they’d have something sensible set up!
Aran: you got a sysadmin for free when you hired a developer! 
Aran: you got a sysadmin for free when you hired a developer!
Yeah, and I’m hoping he’ll have some free time to do sysadmin stuff oh, maybe early in 2023 or thereabouts…
We were going straight through the Rackspace cloud sites smtp for the old forum, which was our most painful time - eventually, they discontinued it, anyway. Then we were on a much more carefully restricted deal also with Rackspace - again, far from ideal. We haven’t activated bulk mail with our ‘new’ provider, but we will do at some point, probably in the not-too-distant future for some of the functionality I’d like us to offer local groups…