Mail server failing SSL check results

[Dimitri]

I used to use this "mail servers test" at from [ssl-tools.net...] as well as the one at [mxtoolbox.com...]

However, now, with SSL Tools.net I get an error :

No connection to the mailservers of xxx could be established.

Results incomplete (unexpected EOF (End of File))

In my logs, I have

postfix/smtpd[9172]: connect from ssl-tools.net[xxx.xx.xxx.xxx]
postfix/smtpd[9172]: SSL_accept error from ssl-tools.net[xxx.xx.xxx.xxx]: Connection reset by peer
postfix/smtpd[9172]: lost connection after STARTTLS from ssl-tools.net[xxx.xx.xxx.xxx]
postfix/smtpd[9172]: disconnect from ssl-tools.net[xxx.xx.xxx.xxx] ehlo=1 starttls=0/1 commands=1/2

In the past, it was working, I didn't change my Postfix configuration. I also tried by disabling entirely my firewall.

I could paste my main.cf and master.cf, but it would take me a while to check and remove all info about my server.

Any idea where to look?

I am adding that, there is no problem in receiving and sending emails, all works, including TLS, (trying from different mail services, my ISP, gmail, yahoo, etc...)

[engine]

I assume the mailserver pings fine, with no errors.

Is the mailserver blacklisted anywhere at all?

Is this a constant error, or just a temporary time out.

[Dimitri]

I assume the mailserver pings fine, with no errors.

Yes.

Is the mailserver blacklisted anywhere at all?

No. But, it's unrelated to the issue, since the ssl-tools.net is to test/check the configuration of a mail server.

Is this a constant error, or just a temporary time out.

The only problem is with ssl-tools.net . Nothing else is producing this error, and the server is working perfectly fine. Now, I don't know what ssl-tools.net is trying to do, at the moment this error occurs. It's possible it is testing for a particular exploit and Postfix is closing the connection. It's possible Postfix was updated..

It's not a big deal, since my mail server works, but I like to get confirmation by external services that it's configured safely.