had to chime in here because i did my homework on this one :) Cheapest/most space would be inbox.eu - 3 eur a year along with 100gb cloud storage and great privacy, has been around forever in the form inbox.lv. I also use Purelymail but that’s sort of a one man project and better if you need multiple domains. There are also some domain registrars who will offer email free or low cost themselves.
oh man I remember how I felt after I found out aghaidh was pronounced like “ai”.
that being said tho (sorry, couldn’t resist ;) irish phonology is wayy more regular than English it’s just a removed to learn coming from English letters because it’s hard not to think of them as standing in for another sound.