"REST API is not yet supported for this mailbox" error for request to a mailbox

Applies to: Power Automate


When you use your account to issue any Outlook REST API request or when you use any Outlook functionality in Microsoft Flow, you may receive the following error message: 


This error can for various reasons:

  • The mailbox is on a dedicated Microsoft Exchange Server or is not a valid Office 365 mailbox.
  • The mailbox is an Outlook.com account that hasn't been enabled yet.
  • The mailbox is not part of an Office 365 plan that includes Flow.


To fix this issue, use one of the following options, as appropriate for your situation. 

Option 1: Migrate your mailbox account

If you don't have a valid Office 365 mailbox, you must submit a request to your Outlook administrator to migrate the mailbox account. Users who don't have administrator permissions can't migrate accounts. For  information about how to migrate the mailbox account, see How to migrate mailbox data by using the Exchange Admin Center in Office 365

Option 2: Wait for your mailbox to update, or request a developer preview account

Because enabling mailboxes on Outlook.com for the Outlook REST API happens over time, your existing Outlook.com account may still be in the queue. You can request a new, enabled Outlook.com developer preview account by sending an email message to outlookdev@microsoft.com.

Option 3: Upgrade your Office 365 plan

The following Office 365 plans include the “Microsoft Flow for Office 365” plan:

  • Office 365 Business Essentials
  • Office 365 Business Premium
  • Office 365 Education
  • Office 365 Education Plus
  • Office 365 Enterprise E1 
  • Office 365 Enterprise E3 
  • Office 365 Enterprise E5


  • Office 365 Enterprise E2 includes the same capabilities as Office 365 Enterprise E1, and Office 365 Enterprise E4 includes the same capabilities as Office 365 Enterprise E3. 
  • Office 365 Enterprise F1 includes the same capabilities as Flow Free. However, a service level agreement is provided, and the number of flow runs is aggregated across all users in an organization.

For more information, see Flow Plan

More Information

Outlook REST API includes the following subsets to enable access to your mailbox data in Office 365, Hotmail.com, Live.com, MSN.com, Outlook.com, and Passport.com.

For more information, see Use the Outlook REST API (version 2.0)