Unlimited on my self hosted mail servers across a dozen or so domains and up to 600 aliases on Fastmail across several domains. I do not have any that I could hand out anywhere as it would get blasted by junk and I would end up having to remove it unless I filtered on a set of GPG keys or something to that effect.

Then for "hand out anywhere" I just use iCloud aliases that I can disable.

Actual inboxes with their separate username@domain and password? Probably about 20, out of which I only really use around 10 and the rest are dormant or I don't really bother checking.

At least one is a role acccount that I look after along with the org that it is for.

My fastmail has 250+ masked addresses and about 10 aliases.