Archiving Emails from a Sendmail Based Email Server
Archiving Incoming and Outgoing Emails Directly
As Sendmail is one of the most flexible mail transfer agent available there is no best practice available. It mainly depends on you environment how your want to create copies of all emails. The recommended way since Sendmail 8.10 is using the libmilter interface to add additional functionality to Sendmail.
A database of available Milter plugins is available at https://www.milter.org. There is also a section for archiving solutions. There are huge differences how those Milter plugins are implemented an work. Unfortunately it is up to you to find the most suitable match for you environment.
In any case, the main target should be having a copy of all email messages delivered to a single archiving mailbox including envelope headers. That mailbox must be accessible by IMAP to make use of MailStore Server's "IMAP Multidrop" profile.
