Sumatra Development leads the field of migrating entire calendar servers to Microsoft Exchange / Office 365 while maintaining meetings, guest lists, guest responses, recurrence patterns, and resource reservations. We migrate Oracle Calendar Server, Oracle Beehive, Apple PostgreSQL icalendar, Kerio Connect, MDaemon, and Zimbra to Microsoft Exchange keeping all meeting information intact. We also migrate calendars server-to-server between Exchange and Office 365 while keeping meetings live with incremental sync.