What Does https://first2host.co.uk/blog/install-exim-email-and-dovecot-on-ubuntu-and-debian-servers/ Mean?
For those who demand a lot more elaborate configurations, such as establishing Exim to relay mail for a number of domains, You will need to edit the configuration file manually:Let’s develop a team vmail with id 5000 and increase a person vmail to that team. Immediately after that we'll alter the proprietor on the /var/mail/# See /usr/share/postf