Contents of cloud-based archive are the same as contents of on-premises primary mailbox

Original KB number:   2987546

Problem

Assume that you have a hybrid deployment of on-premises Microsoft Exchange Server and Exchange Online in Microsoft 365. When you view the cloud-based archive mailbox of a user, archived items are not displayed. Instead, the contents of the cloud-based archive mailbox are the same as the contents of the user's on-premises primary mailbox.

Cause

This issue may occur if the user principal name (UPN) of the user's on-premises Exchange mailbox has a suffix that makes it differ from the UPN of the archive mailbox. For example, this issue may occur if the UPN of the user's on-premises mailbox is joe@contoso.com and the UPN of the user's archive mailbox is joe@contoso1.com.

This issue may also occur if your on-premises Exchange organization isn't federated with Exchange Online correctly.

Solution

Make sure that your on-premises Exchange organization is correctly federated with Exchange Online. For more info, see Configure a federation trust.

More information

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