Enforced TLS tunnel from Zoho Mail

Enforced TLS tunnel from Zoho Mail

Hi,

I am looking for some advice regarding enforced TLS tunnel being set up from Zoho mail.

I  do not want to use opportunistic encryption and I want to make sure all incoming and outgoing email are encrypted with TLS.
Is it possible using Zoho or do I need to use third party for setting up enforced TLS tunnel ? 
Thanks