Proxmox Mail Gateway Community

✔ Unlimited users
✔ Unlimited Domains
✔ Integration with LDAP and Microsoft Active Directory
✔ Scan for viruses - ClamAV
✔ Create HA Cluster *
✔ Unlimited use of the public support forum
✔ Access to updates from the Enterprise repository for 12 months
✔ Ability to extend support - yes

and:

✔ Spam Detection with Commtouch's RPD and GlobalView
✔ Object-oriented rule system
✔ Daily end-user spam report, including web quarantine management
✔ Fully customizable outbound email filtering
✔ Support multiple mail servers as transport
✔ Custom Branding
✔ Scheduled Backup and Restore
✔ Message Tracking Center
✔ Statistics
✔ Syslog server support

Delivery time - from 2 to 7 days