Email archiving provides lots of benefits to your company. Piler is a feature rich open source email archiving solution, and a viable alternative to commercial email archiving products; check out the comparison with Mailarchiva.
Piler has a nice GUI written in PHP supporting several authentication methods (AD/LDAP, SSO, Google OAuth, 2 FA, IMAP, POP3). Be sure to try the online demo!
- archiving and retention rules
- legal hold
- digital fingerprinting and verification
- full text search
- tagging emails
- view, export, restore emails
- bulk import/export messages
- audit logs
- support for Google Apps and Office 365
- and many more