If you build new services, websites, or startups, you usually want to create an email address for your domain name. Maybe something like firstname.lastname@example.org. And ideally you want it for free.
I thought I'd quickly outline and compare the main solutions for that here:
postale.io (simplest but 5 mailboxes per domain max),
Yandex Mail (most capabilities but ads and not as intuitive),
Zoho Mail free plan (5 mailboxes max, 1 domain only and webmail only),
Migadu free plan (not so great IMO as it's limited to 10 outgoing emails per day max and adds a "Sent via Migadu" at the end of every email).
Overall I'd say postale.io is probably the easiest choice for the vast majority of people due to its simplicity. The creation process is fast and simple, the UI is intuitive, and the most technical part (DNS setup) is handled for you if requested. However it's currently limited to 5 mailboxes per domain.
Yandex in the other hand offers unlimited mailboxes per domain, but is harder to grasp (partly because its UI is all over and partly because there's a lot in russian).
Hope this is helpful! What do you think?