Mailbox connection fails: Connection closed (No commands sent) Help please

[Robert L Mathews]

On 12/7/21 2:49 PM, Alexander Dalloz wrote:

> Use a not expired certificate.
> 
> $ openssl s_client -connect 194.163.45.150:993
> CONNECTED(00000003)
> depth=3 O = Digital Signature Trust Co., CN = DST Root CA X3
> verify error:num=10:certificate has expired
> notAfter=Sep 30 14:01:15 2021 GMT

That error's happening because you (Alexander) are using an old openssl 
version that has the problem described on:

  https://www.openssl.org/blog/blog/2021/09/13/LetsEncryptRootCertExpire/

That's not the problem that the original poster is having unless 
Thunderbird also has the same problem, which it may; see:

 
https://community.letsencrypt.org/t/note-regarding-transition-to-r3-intermediate-with-firefox-or-thunderbird/140049

 
https://www.arcanoae.com/adding-lets-encrypts-new-root-and-intermediate-certificates-to-mozilla-applications/

In any case, this works fine with OpenSSL 1.1 or later:

  $ openssl s_client -connect mail.sizzelicks.com:993
  ...
  * OK [CAPABILITY IMAP4rev1 SASL-IR LOGIN-REFERRALS ID ENABLE IDLE 
LITERAL+ AUTH=PLAIN AUTH=LOGIN] Dovecot (Ubuntu) ready.

-- 
Robert L Mathews, Tiger Technologies, http://www.tigertech.net/