Cloud-based Message Recall in Exchange Online

stutoronto It won't change for external recipients who are not hosted in EXO since the functionality is only available on the servers in the EXO datacenters. However, as noted in my previous comments further above we're looking to support recall between EXO tenants later this year but ONLY when the recipient's tenant admin enables/allows it. 

Our legal team assures me that once the message is delivered to the recipient's mailbox the recipient (or more accurately, the recipient's tenant as data controller) now owns that message, and only the recipient's tenant (represented by the admin) gets to decide whether it's recallable or not. Similarly, IRW where the US Gov owns all mail and letters in a person's physical mailbox  - it's a crime for the sender of the letter to take it ('steal it') from the recipient's mailbox. 

FWIW, even without the ability currently to recall from recipients outside your tenant, it's clearly not moot for millions of users. Despite being limited right now to just internal recipients millions of recalls are triggered in the service daily (with ~98% success rate; the number of failed recalls because the recipient is external is < 0.00005%).