Talk to your IT or Microsoft 365 admin about co-locating them. If your primary mailbox is in on Exchange Server, for example, and your archive account is in Exchange Online in Microsoft 365, you won't be able to use your online archive. Note: In order for your archive mailbox to work with Outlook for Mac both your archive and primary mailboxes must be either on an Exchange Server (on-premises) or on Exchange Online in Microsoft 365 (cloud).
