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Is there a good way of using it to archive mail in a way that can be searched (if needed) at a later date ?
If it fits your use case, Thunderbird will do this, too.
I find Thunderbird's indexing fantastic. A workstation running Thunderbird configured to fully sync all mail in all folders provides a good poor mans email search solution.
For searching only one or two accounts, just add them to Thunderbird and let it sync.
For searching your entire server, consider creating an archive mailbox and keeping copies of all email using
Bcc and BccMode.
If you don't mind Google reading your mail, you could create a Gmail account that syncs all the email you want to search - either lots of individual mailboxes or using Bcc / BccMode.
There's a wiki page for
MailArchiva, but the version it uses hasn't been updated since 2009.