Symptoms
- 
The mail log
/var/log/maillogcontains warnings:May 4 12:13:47 server99 dovecot: config: Warning: Obsolete setting in /etc/dovecot/conf.d/11-plesk-security-ssl.conf:2: ssl_protocols has been replaced by ssl_min_protocol
May 4 12:13:47 server99 dovecot: doveconf: Warning: NOTE: You can get a new clean config file with: doveconf -Pn > dovecot-new.conf
May 4 12:13:47 server99 dovecot: doveconf: Warning: Obsolete setting in /etc/dovecot/conf.d/11-plesk-security-ssl.conf:2: ssl_protocols has been replaced by ssl_min_protocol
May 4 12:13:47 server99 dovecot: config: Warning: NOTE: You can get a new clean config file with doveconf -Pn > dovecot-new.conf
May 4 12:13:47 server99 dovecot: config: Warning: Obsolete setting in /etc/dovecot/conf.d/11-plesk-security-ssl.conf:2: ssl_protocols has been replaced by ssl_min_protocol 
Cause
The Dovecot configuration contains an obsolete SSL version directive. The ssl_protocols directive has been replaced with ssl_min_protocol in new versions of Dovecot but is still present in the configuration.
Resolution
- 
Connect to the server via SSH
 - 
Open the file
/etc/dovecot/conf.d/11-plesk-security-ssl.confin any text editor (For example, vi editor) - 
Find the
ssl_protocolsline and comment it, for example:ssl_protocols = TLSv1 TLSv1.1 TLSv1.2
Should become:
#ssl_protocols = TLSv1 TLSv1.1 TLSv1.2
 - 
Restart Dovecot:
# systemctl restart dovecot