Just for the records, we solved it modifying the 10-ssl.conf dovecot’s file.
This was the current 10-ssl.conf file:
ssl = required
ssl_cert = </home/Minenge/conf/web/minenge.com.br/ssl/minenge.com.br.pem
ssl_key = </home/Minenge/conf//web/minenge.com.br/ssl/minenge.com.br.key
ssl_dh=</etc/ssl/dh.pem
#ssl_cert = </etc/ssl/dovecot/dovecot.pem
#ssl_key = </etc/ssl/dovecot/dovecot.key
ssl_min_protocol = TLSv1.2
ssl_cipher_list = PROFILE=SYSTEM
ssl_prefer_server_ciphers = yes
And this is the modified file:
ssl = yes
ssl_cipher_list = ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:DHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES256-SHA384:ECDHE-RSA-AES256-SHA384:DHE-RSA-AES256-SHA256
ssl_min_protocol = TLSv1.2
ssl_prefer_server_ciphers = yes
ssl_cert = </usr/local/hestia/ssl/certificate.crt
ssl_key = </usr/local/hestia/ssl/certificate.key
# From and up to version 2.2
#ssl_dh_parameters_length = 4096
# From version 2.3
ssl_dh = </etc/ssl/dhparam.pem
Once modified and dovecot restarted, it works fine again.