[stunnel-users] Microsoft Exchange 2010 - SMTP issue

mahdi at kadtekautomation.com mahdi at kadtekautomation.com
Thu Feb 4 03:07:00 CET 2016

Hey all,

Has anybody here been successful connecting to Microsoft Exchange 2010 servers usnig STunnel? Here is what I have in my stunnel.conf:

cert = stunnel.pem
socket = l:TCP_NODELAY=1
socket = r:TCP_NODELAY=1
client = yes

accept =
connect = smtp.ex3.secureserver.net:587

And this is what I see in the log:

2016.02.03 18:55:14 LOG5[63]: Service [ssmtp] accepted connection from
2016.02.03 18:55:14 LOG5[63]: s_connect: connected
2016.02.03 18:55:14 LOG5[63]: Service [ssmtp] connected remote server from
2016.02.03 18:55:14 LOG3[63]: SSL_connect: 140770FC: error:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol
2016.02.03 18:55:14 LOG5[63]: Connection reset: 0 byte(s) sent to SSL, 0 byte(s) sent to socket

I am quite sure that my server address and port is correct, and obviously the other application is pushing data to stunnel. Seems like what's coming back from server is puzzling. Any help regarding this?
Thanks, Mahdi.
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