When using Roundcubemail-1.2.12 LTS, the system is using PHP 5.4...which is different from the one used in the docker.
My imap server is configured not to accept SSLv2 and SSLv3.
I was trying to pass some parameters such as "TLS1, TLSv1, TLSv2" to the "ciphers" config option in imap_conn_options, but nothing seems to work.
From de roundcubemail docker terminal I type openssl s_client -connect my.ip:993 -tls1 (tls1_1 and tls1_2) and I get the exact same error on my imap server:
" TLS handshaking: SSL_accept() failed: error:14094410:SSL routines:SSL3_READ_BYTES:sslv3 alert handshake failure: SSL alert number 40"
Thanks