If a developer stops supporting an old version of an app, does that old version stop working?

Question

iOS

There is an email application.
The developer stated that he stopped supporting the old version.
But the old version still works. Push notifications arrive regularly (this is a mail application).
Does deprecation of an old version of an application always mean that that old version will no longer work?

Answer 1

No, it doesn't.
If the application depends on the server API and the developer changes it or prohibits the use of older versions of his application, then it will not work.
If the application does not depend on another server, it will work until it is updated to a non-working version or until the protocol of the service with which it works (in this case, the mail protocol) is changed.