Test starttls smtp auth

Category: sysadmin Generated on 2017-12-12 source: source source: source2

If the SMTP requires STARTTLS, telnet can't be used.

We can use openssl:

$ openssl s_client -starttls smtp -connect host:port -crlf -ign_eof

to initiate and encrypted connection.

Then command AUTH LOGIN start auth process:

AUTH LOGIN
334 VXNlcm5hbWU6 ( Server returns username as a base64 string )
--base64 encoded username--
334 UGFzc3dvcmQ6 ( Server returns password as a base64 string )
--base64 encoded password--
235 Authentication succeeded