Zimbra - is it possible to authorize only from the local network for a group of users?

Question

User identification

Good afternoon!
Faced with an unusual situation, you need to implement the ability to authorize individual users only within the network. That is, some users can log in from any external address, and some - only from the local network. The same users are already blocked by means of postfix sending to external addresses.
Is it possible to implement this?

Answer 1

As far as I know, you can solve everything using the Zimbra Web Console
Create a service class and uncheck external access pop and imap
for a group of users, replace the service class with the created one
To start testing on some user

Answer 2

VPN solves such issues.