Disable IMAPS and POPS for the iredmail

All clients are forced to use IMAPS and POPS for better security by default. If you want use POP3/IMAP, please update below two parameters in dovecot.conf and restart Dovecot service

nano /etc/dovecot/dovecot.conf

disable_plaintext_auth=no

ssl=yes

/etc/init.d/dovecot restart

Again, it’s strongly recommended to use only POP3S/IMAPS for better security.