Is it possible to have Logwatch send daily emails without actually installing Postfix? I want to keep my server light and installing an MTA just because of Logwatch seems overkill. Or will I need Postfix anyways for admin work?
You can install a relay-only MTA like nullmailer instead of postfix. It still has the sendmail-like interface many programs expect, but does nothing except sending mails to an upstream MTA. This is about as light-weight as you can reasonably get.