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Łukasz Zaroda
Asked: 2015-05-05 17:10:10 +0800 CST

Mail server not picked up by TLS diagnostic tools

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I have mailing server under mail.luken-tech.pl . Can anyone explain how this: https://www.ssllabs.com/ssltest/analyze.html?d=mail.luken-tech.pl&hideResults=on shows "Assessment failed: Unable to connect to server", this: http://www.checktls.com/perl/TestReceiver.pl gives me "Cannot connect to server (reason: Connection refused)".

But this:

openssl s_client -starttls smtp -connect mail.luken-tech.pl:587 -tls1 -ign_eof
openssl s_client -starttls smtp -connect mail.luken-tech.pl:587 -tls1_1 -ign_eof
openssl s_client -starttls smtp -connect mail.luken-tech.pl:587 -tls1_2 -ign_eof

Works perfectly fine, and my server generally seems to work ok? :) Why any testing tool cannot connect to my smtp? It bothers me because I configured one server before, and I didn't have something like that. Should I care about this?

email-server

1 Answers

  1. Best Answer

    Can anyone explain how this: https://www.ssllabs.com/ssltest/analyze.html?d=mail.luken-tech.pl&hideResults=on shows "Assessment failed: Unable to connect to server"

    SSLLabs only support HTTPS Testing. Your mail server speak with STARTTLS and SMTP protocol. The error message confirm the limitation 

    Ports other than 443 not supported

    This http://www.checktls.com/perl/TestReceiver.pl gives me "Cannot connect to server (reason: Connection refused)"

    This test will send email to your host via default port i.e. port 25, not port 587 as you intended. Apparently, port 25 on your server is closed

    $ telnet mail.luken-tech.pl 25
Trying 91.196.50.126...
telnet: connect to address 91.196.50.126: Connection refused
telnet: Unable to connect to remote host

    If you want test, you can use your mail client (for example thunderbird), native openssl (you have done it) or swaks

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