Dovecot is an open source IMAP and POP3 email server for Linux/UNIX-like systems, written with security primarily in mind. Dovecot is an excellent choice for both small and large installations. It's fast, simple to set up, requires no special administration and it uses very little memory.
Dovecot config path is: /etc/dovecot/dovecot.conf
Dovecot log path is: /var/log/maillog
Build dovecot conf: /scripts/builddovecotconf
Summary: Dovecot after installation let's all mailbox users to log into their mailbox & read emails / compose / delete emails & so on. Dovecot authenticates users by Exim & when you send an email, dovecot passes the email to Exim, Exim sends it to remote or local SMTP & then gets it delivered or error for non-delivered email.
IMAP uses port 143 , but SSL/TLS encrypted IMAP uses port 993
POP uses port 110 , but SSL/TLS encrypted POP uses port 995