Hello Basti. Maybe you tried LE too early when it was not universally accepted as a trusted CA ?
On Monday, February 20, 2017 2:22 PM, basti <ba...@unix-solution.de> wrote: Hello, I had the same problem. LE is not in the CA list. Best Regards, On 17.02.2017 17:58, Bastian Sebode wrote: > Hello Folks, > > my StartCom SSL-Certificate expires soon and so I wanted to switch to > Let's Encrypt Certificates instead. Unfortunatelly Thunderbird seems not > to like it, although all -tested- other Clients work without any problems. > > When I connect with Thunderbird it sends an "Encrypted Alert" directly > after the TLS handshake although Dovecot wants to continue the session. > > In the Dovecot Log it says: > Feb 17 17:27:17 imap-login: Debug: SSL: where=0x20, ret=1: SSL > negotiation finished successfully [82.100.242.26] > Feb 17 17:27:17 imap-login: Debug: SSL: where=0x2002, ret=1: SSL > negotiation finished successfully [82.100.242.26] > Feb 17 17:27:17 imap-login: Warning: SSL alert: where=0x4004, ret=554: > fatal bad certificate [82.100.242.26] > > But the certificate is okay, cause it works with other Mailclients and > openssl also says so. What certificate is Thunderbird complaining about? > > Thunderbird says something like "There's no supported authentication > method". I don't use any Certificates for Client Authentication, neither > in Dovecot nor in Thunderbird. When I do, it fails the same way. > > Weirdly my friend uses the same Dovecot Version with Let's Encrypt on > his Server and it works with Thunderbird without any flaws. Mine fails > the same way in his Thunderbird and also in a fresh installation. > > After two weeks of investigating I still have no clue why it behaves > like this. > > I uploaded two Wireshark tracefiles, further logs and dovecot -n, may be > someone sees any possible reasons for this weird behavior or has any > further tips on solving this issue. > https://sebode-online.de/dovecot-letsencrypt/ > > Every hint is highly appreciated! > > Best Regards > Bastian >