Test Mail Server for Inbound TLS

Here’s how to test if a mail server supports TLS using a windows pc:

1. nslookup
   > set q=mx
   > google.com
2. The results:
   google.com   MX preference = 100, mail exchanger = google.com.s9a1.psmtp.com
   google.com   MX preference = 300, mail exchanger = google.com.s9b1.psmtp.com
   google.com   MX preference = 200, mail exchanger = google.com.s9a2.psmtp.com
   google.com   MX preference = 400, mail exchanger = google.com.s9b2.psmtp.com
3. > exit
4. telnet google.com.s9a1.psmtp.com 25
5. After connected type:
   ehlo google.com
6. If you see this in the output, the mail server supports inbound TLS communication:
   250-STARTTLS