[TriLUG] recommendations for email archiver

[Chris Bullock]

I am looking for some type of email archiver we can implement so that management can easily search any mail that has been sent/received to and from our mail server.
We are currently running Postfix.  We would need for any mail sent/received by the mail server to be archived, this includes intra office mail.  The product/software would need a very good GUI so that non technical people could search the archive.  We would like a retention rate of at least 5 years.

Thanks in advance,
chris