Yes, it is possible to migrate IceWarp to Microsoft 365 including contacts and calendars, but it typically requires separate steps for different types of data. Emails are usually migrated through IMAP, while contacts and calendars are exported and imported using supported formats. In one situation I experienced, a user used the SysInfo IMAP Backup Tool to transfer emails from IceWarp to Microsoft 365. The tool connected to the IceWarp mailbox, displayed folders for preview, and then migrated emails while maintaining attachments and folder hierarchy. After that, contacts were exported from IceWarp as CSV files and calendars as ICS files. These files were then imported into Microsoft 365. This method allowed the user to migrate IceWarp to Microsoft 365 with all essential email, contact, and calendar data.
Read more: https://www.sysinfotools.com/blog/migrate-icewarp-to-microsoft-365/