iPhone email protocol

You’re welcome; keep well.

You might want to consider using the gmail app, which has a better interface than the built in Apple mail app. And it supports Push. Google supported Push with the Apple app at one time, but they dropped it when they released their own mail app.

Go to Settings/Passwords & Accounts. Tap on an account and it will tell you at the top what kind of account it is. It will say Exchange, IMAP or POP, or the name of the provider for anything else. Things like gmail, yahoo, etc are their own protocol that is IMAP based, but not exactly IMAP.

Gmail is a modified IMAP protocol, unless you have the paid enterprise version, which is MS Exchange.