Manually Test TLS

One issue that comes up often in testing SMTP connections is in regards to TLS. 

When we need to do this it adds a layer of complexity that has some think it cannot be done.  This is the greatness of openssl and below is what you’ll need (bare bones of course) to manually test:

openssl s_client –connect <recipient MTA>:<port> -starttls smtp

You will also need to provide information concerning the TLS certificate exchange, you’ll get a prompt to type the remaining SMTP commands like normal (e.g. MAIL FROM, RCPT TO:, etc).  You can also add specific paths to reference a custom TLS certificate location.