Support Only the Necessary Protocols

Description

Dovecot supports the IMAP and POP3 protocols, as well as SSL-protected versions of those protocols. Configure the Dovecot server to support only the protocols needed by your site. Edit /etc/dovecot/dovecot.conf. Add or correct the following lines, replacing PROTOCOL with only the subset of protocols (imap, imaps, pop3, pop3s) required:

protocols = PROTOCOL

If possible, require SSL protection for all transactions. The SSL protocol variants listen on alternate ports (995 instead of 110 for pop3s, and 993 instead of 143 for imaps), and require SSL-aware clients. An alternate approach is to listen on the standard port and require the client to use the STARTTLS command before authenticating.