How to organize additional protection of remote access to Exchange Server?

Question

Microsoft Exchange

Good day!
There is a corporate mail server based on MIcrosoft Exchange server 2010. For remote access to mail from the Internet, a port is forwarded to the server, ova is activated, and two-factor authorization protection is installed.
Through the Web browser, the scheme works out with a bang, but there is one thing - mobile clients, which in the phone settings can register the server address, credentials and freely download / send mail via the phone.
I would like to somehow organize additional protection for such connections, for example, issue an additional certificate and not let it into the mail without it. Is there such a way, and where can I read about it? If there are other options, I'd be happy to hear about them.

Answer 1

The MS sites are a treasure trove of wisdom for any user of their products, as are books on MS products.
Technet, MSDN are things to remember when administering MS products.
For example https://technet.microsoft.com/en-us/library/bb4307...