What does the error message "Could not load folders from Microsoft: The mailbox is either inactive, soft-deleted, or is hosted on-premise" mean?

This error message means that sync.blue® cannot access the contacts of the affected Microsoft 365 user because Microsoft does not provide it as an active Exchange Online mailbox.

Possible causes:

• The Exchange mailbox is inactive
• The user was recently deleted (soft-deleted)
• The mailbox is on-premise or not fully migrated to Exchange Online

Important for Microsoft Teams

Even when synchronizing with Microsoft Teams, an active Exchange Online mailbox is always technically required. Contacts can only be synchronized with Teams if the user also has an active, licensed Exchange mailbox in Microsoft 365.

👉 Therefore, this error message occurs particularly frequently with Teams synchronizations.

Make sure that an active Exchange Online mailbox is available.