My email addressing strategy: multiple personas / custom domains / aliases

Thanks @bulletproof for your detailed feedback.

However I do not see a substantial benefit adding a infrastructure domain, but maybe I am missing sth.

bulletproof:

The only structural weakness:

If Proton or SimpleLogin ever becomes unavailable (account lock, policy change, billing issue, political issue), all three personas go dark at once.

If I have an issue with Proton, I think I could forward all my aliases (generic SimpleLogin and owned domains ones) to another email provider in a matter of minutes. Not need of infrastructure domain.

But an issue with SimpleLogin is way more problematic. I have not used any other email alias service, so I do not know if the migration of my owned domain aliases would be straight forward; and about the generic SimpleLogin aliases, with or without infrastructure domain, is gonna be highly time consuming, in any way, I would need to reset every online account email with generic SimpleLogin alias.

But since SimpleLogin is owned by Proton, any problem with one of them would probably affect the other.

So adding the infrastructure domain just help a migration from Proton, but this is a minor issue. The real problem is migrating from SimpleLogin and on that this solution does not help.