iPhone 16 email issues after September update

I bought a iPhone 16 in September and after an update in September, my mail had problems. 

It doesn’t populate. Just sometimes empty email slots or part of a message.

Emails are missing. Problems sending. 

And my phone gets very hot continually trying to connect and receive emails sometimes emails appear hours or days later. 

I have been through all Apple fixes numerous times and still it does the same. I asked for a new phone just to try it. Refused. 

Usually after I delete the accounts and re add the account, it works well the longest time of one month. 

The solution-none. It is with the Apple engineers since September. 

I happens with my iCloud account, Gmail and Roadrunner. 

[Edited by Moderator]

Original Title: 16 email problem