Check your smtp security with TLS receiver test
I’ve used a webservice to check the TLS settings on a secured website numerous times (ssllabs.com). But I’ve only recently discovered a TLS/SSL testing service that checks if third parties can securely deliver mail on you mailserver.
Using http://www.checktls.com/ I was able to test my mailserver setup. This uncovered a minor issue with my TLS certificate chain. After a small fix I was able to verify that third parties should be able to securely deliver mail to my setup. Nice 😉