Email app for iOS that filters out unknown emails

Is there an email app for ios that lets you authorise email addresses that you want to see mail from bit like the call blockers on phones so that spam still goes to spam, none spam or unauthorised goes into a holding folder and just authorised email arrives in inbox.

whoever your email is with may have such option(s) / features...

I can 'blacklist' addresses on my gmail, and it just filters those out...

It's usually not down to the app, but down to the email server/host to do things like you just suggested...

Don’t want to blacklist, too many, want my inbox to be based on a list I provide and which I can maintain.

Don’t want to blacklist, too many, want my inbox to be based on a list I provide and which I can maintain.

Blacklist was just an example, cause that's what I use (rather than multiple lists)

My point was, I doubt you will find an APP to do what you're needing, as such things are usually done at the host side...