Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I need a command to connect to POP3 server, set startTLS, and get secure connection. I neet something to use like telnet. Is there any program that can achieve it?

--edit I'm just trying to write similar SMTP server, and I'd like to test in time handshake done by starttls. Is there something to help me?

share|improve this question
If you are writing an SMTP server, it would only take a few minutes to knock up a client to interact with it. – Paul Jan 17 '13 at 20:52

Yes, you can use openssl to do this:

$ openssl s_client -crlf -connect -starttls pop3

This will initiate the session and get the certificate exchange going. You'll see the certificate exchange messages going back and forth, then the standard pop3 prompt:

+OK Hello there.
user username
+OK Password required.
pass passw0rd
+OK logged in.
share|improve this answer
is there a way that client doesn't authenticate on start, but when I type starttls? – oneat Jan 16 '13 at 10:12
@oneat Not that I know of, can you add more detail to your question about what you are trying to achieve and it will help focus the answers better – Paul Jan 16 '13 at 10:22
usually ssl starts when starttls is supplied, but in your example it's supplied instantly (as I understand). I want to write starttls by myself to server and not to be written by opensll. – oneat Jan 16 '13 at 10:26
@oneat Yes, I understand that from your previous comment, it would be helpful if you could edit the question to add more detail about what you are trying to do. – Paul Jan 16 '13 at 11:06

Isn't it easier to just set up whatever connects via POP3 to use SSL/TSL in the first place? Better use IMAP if you can, the protocol is much more robust and moreover efficient

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.