Since we released cloud-based Message Recall in April 2023 (see Cloud-based Message Recall in Exchange Online), we’ve continued to expand where and how recall works – including support for Outlook on the web and mobile, recipient recall notifications, a maximum recallable message age, and support for external round-trip routing (see Exchange Online Message Recall Updates).
Until now, all these capabilities shared one boundary: Message Recall only worked within a single tenant. Today, we’re pleased to announce one of our most requested cross-organization enhancements:
- Cross-Tenant Message Recall, controlled by a tenant admin allow list
The intra-tenant boundary
By design due to privacy concerns, Message Recall operates within the Exchange Online service boundary, and until now it has been limited to intra-tenant messages – those where the sender and the recipients belong to the same Microsoft 365 tenant. When a sender tried to recall a message they had sent to recipients in a different tenant, the recall would fail, even between organizations that work closely together and trust one another.
Customers told us this was a gap. Partners, subsidiaries, and affiliated organizations that collaborate daily across tenant boundaries wanted the same recall experience they already had inside their own tenant.
Introducing cross-tenant Message Recall
With Cross-Tenant Message Recall, a tenant admin can add other Microsoft 365 tenants to an allow list. Once a tenant is on the list, senders from those allow-listed tenants can recall messages they’ve sent to recipients in the receiving tenant – just as they would for an intra-tenant recall.
Control sits with the receiving tenant – the organization whose users received the messages. A cross-tenant recall is only honored when the receiving tenant’s admin has explicitly allow-listed the sender’s tenant. This keeps the receiving organization in full control of which external tenants are permitted to recall messages from its users’ mailboxes. The feature is disabled by default; no cross-tenant recall occurs until an admin adds at least one tenant to the allow list.
How it works
Consider two organizations that work together, Contoso and Fabrikam, both of whom are hosted in Microsoft 365:
- A Contoso admin adds Fabrikam’s tenant to Contoso’s cross-tenant recall allow list.
- A sender at Fabrikam recalls a message they previously sent to a recipient at Contoso.
- Because Contoso has allow-listed Fabrikam, the recall is honored and processed like a standard recall against the Contoso recipient’s mailbox.
If Fabrikam is not on Contoso’s allow list, the recall fails and the Fabrikam sender will see in the recall status report that the message can’t be recalled across organizations. Allow-listing governs inbound recalls into the receiving tenant, so each organization decides independently which external tenants it trusts to recall messages from its mailboxes.
Configuring with Exchange Online PowerShell
Admins can configure these settings using Exchange Online PowerShell.
Enable or disable cross-tenant message recall for the tenant. Setting this parameter to $True turns on the capability; $False (default) turns it off:
Set-CrossTenantRecallConfiguration -CrossTenantRecallEnabled [$true | $false]Specify external tenants to add or remove from the allowed list. Add the tenant IDs of the organizations you trust to perform recalls:
Set-CrossTenantRecallConfiguration -AllowedSenderTenantIds @{Add="<tenantId 1>","<tenantId 2>"}; {Remove="<tenantId 1>","<tenantId 2>"} To find the tenant ID of the sending tenant (who will send recall request), the sending tenant administrator can run the following command:
Get-ConnectionInformation | fl *tenantid*What senders and recipients see
When a sender in an allow-listed tenant recalls a message, recipients in the receiving tenant experience the recall exactly as they would an intra-tenant recall. If the receiving tenant has enabled recipient recall notifications, those notifications apply to cross-tenant recalls as well. If the sender’s tenant is not on the receiving tenant’s allow list, the sender receives a notification that the message can’t be recalled across organizations.
Availability
Cross-Tenant Message Recall will start to deploy to worldwide, GCC, GCC High, DoD and Microsoft 365 operated by 21Vianet starting mid-August, completing by mid-September. We hope you’ll find this enhancement useful, and we look forward to your feedback.
Microsoft 365 Messaging Team
