Connect to SMTP server using STARTTLS

openssl s_client -starttls smtp -crlf -connect 127.0.0.1:25
Allows you to connect to an SMTP server over TLS, which is useful for debugging SMTP sessions. (Much like telnet to 25/tcp). Once connected you can manually issue SMTP commands in the clear (e.g. EHLO)
Sample Output
$ openssl s_client -starttls smtp -crlf -connect smtp1.google.com:25
CONNECTED(00000003)
depth=1 /C=ZA/ST=Western Cape/L=Cape Town/O=Thawte Consulting cc/OU=Certification Services Division/CN=Thawte Premium Server CA/emailAddress=premium-server@thawte.com
verify error:num=19:self signed certificate in certificate chain
verify return:0
---
Certificate chain
<...>
---
220 smtp.google.com ESMTP

7
By: realist
2009-08-19 08:37:24

What Others Think

Great !
CodSpirit · 478 weeks and 5 days ago

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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