We installed Postfix as the default mail handler on our Gentoo box during the base installation. There are various other MTA’s to choose from, but I prefer Postfix. Not because it is better, but because it is the one with which I “grew up”. This HOWTO is divided in two sections: for a primary MTA, and for a secondary MTA.
Postfix as a Secondary MTA
gentoo ~ # nano -w /etc/postfix/main.cf
… mydomain = groenheide.org.za …
gentoo ~ # nano -w /etc/mail/aliases
… root: robert …
Update the indexed version for Postfix to use:
gentoo ~ # postalias hash:/etc/mail/aliases