I need to establish forced TLS mail (Outbound) to sepcified domain(Partner Company).

ExchangeMBX2013- CAS ---- >SMTP relay---->Mail Security system-----> external---->Specifed domain.

Mail security system have to receive forced TLS from SMTP relayed and then deliver the TLS mail to external.

I think belows action plan will be required, any other options to do for achievement?

- Public CA for TLS install on Exchange server

- Forced TLS setup in SMTP relayed server  for the domain

• Edited by tanale 1 hour 31 minutes ago

You don't necessarily need a public certificate if you own the relay server and can install your own CA's root certificate or otherwise make it trust your self-signed or internally issued certificate, but a public certificate might be easier.

You'll make a send connector that points to the relay server and set -RequireTLS:$True.