Compare MailSite 11 with self-managed Exchange Server Subscription Edition (SE). Exchange Online and Microsoft 365 are separate offerings. The comparison covers deployment and selected capabilities, not complete feature parity.
| Area | MailSite 11 | Exchange Server SE |
|---|---|---|
| Classic Outlook | MAPI over HTTPS for mail, calendars and contacts. Test the exact Outlook build and required workflows. Outlook compatibility | MAPI over HTTP is enabled by default for Outlook connections. Client access architecture |
| Browser access | ExpressPro provides mail, calendars and contacts through MailSite's HTTP service. ExpressPro | Outlook on the web provides browser access. Exchange architecture |
| Web service deployment | HTTPMA serves webmail and routes EWS, ActiveSync and MAPI requests to MailSite workers; no separate IIS installation is required. Web services guide | Setup requires Windows components, including IIS components, and preparation of Active Directory. Exchange prerequisites |
| Administration | Desktop and browser Console share the interface for domains, mailboxes, services and security. MailSite Console | Mailbox servers are administered through the Exchange admin center and Exchange Management Shell. Server roles |
| Availability design | Clustering options use shared MailSite storage. Plan storage availability, networking, load balancing and backup together with Rockliffe. Hosting and clustering | Database availability groups provide database replication and recovery across Mailbox servers. High availability architecture |
Outlook & Client Compatibility
MailSite also provides EWS, ActiveSync and IMAP/POP/SMTP access. Match each client to its supported connection method using the compatibility matrix. Classic Outlook, New Outlook, Outlook for Mac and mobile Outlook have different capabilities; a successful test in one does not establish support for another.
Before replacing Exchange, test shared and delegated access, meetings, rules, applications and any compliance or archiving integrations your organization depends on. Confirm unsupported workflows before scheduling a cutover.
Compare the full deployment
Use the cost comparison alongside your storage, backup, administration and migration requirements. The cost examples state their assumptions and do not establish equivalent features or guaranteed savings.
Review deployment guide · Migration guidance · Request a demo
Sources checked October 5, 2026: the linked Microsoft documentation and the MailSite 11 Administrator Guide. Check the release notes for the build you plan to deploy.