@lightweight I feel your pain. Email causes us more support issues than anything else. We had to relent with our transactional emails and corporate ones, using AWS SES and Google Workspace :/ we just couldn't keep operating without emails getting through. MS recently blocked a whole /24, for a handful of spam emails sent from a single IP address - that was marked in RIPE DB as being in a /28, but nope, block the whole /24.
@karlaustin Yeah, they run roughshod over the rest of the 'net and legitimate email providers like 800lb gorillas (but without the grace and thoughtfulness of actual gorillas).