For years now I’ve used telnet as a quick and easy way to check to see if the most basic network functionality of a service like http is working. I.e. I telnet to port 80 and see the raw server communication. Very helpful in debugging network services. Where it fails is when you get into SSL services. Telnet to port 443 and sure you’ll see you connect, but your not going to be doing an SSL handshake.

So I finally did a little googling and ran across this gem:

openssl s_client -connect

And now I have SSL handshake and my raw plaintext interface that telnet provided.

Works great for all my ssl service troubleshooting (imap/pop/https/etc..).

Found the info at this site: