[aranelsurion]

I assume by "hard limit on the number of emails" you mean daily sending limits, which is quite high for a personal user (500 per day)? If that's the case, Gmail also seems to have a similar limit.

Or do you mean there's a hard limit on total number of emails you can store?

[doctoboggan]

Sorry for the confusing wording, I meant email accounts. It looks like you can only share the domain in your apple family sharing plan which means only 6 different accounts.