Exchange Online Rolls Out Improved Message Recall

Replaces Older Outlook-Based Message Recall

At Ignite 2019 (the last worthwhile event), the Exchange engineering group reported that they were working on a new version of the much-derided message recall feature. I say much-derided because message recall didn’t work most of the time. Microsoft said that Exchange Online users tried to recall messages 800,000 times daily at a 40% success rate. Given the current size of Exchange Online, that number can only have grown since late 2019, so more than half a million people are disappointed daily when they can’t recall a message.

Recall message is a feature that’s almost as old as Outlook for Windows. In the early days of Exchange, the simpler form of networks, fewer external messages, and a less diverse set of clients meant that message recall had some prospect of success. The old mechanism declined over time and badly needed refurbishment.

Deploying Now to Tenants Worldwide

Microsoft announced the new message recall in October 2022 in message center notification MC445411. The last update on 24 January said that the roll-out would start in mid-February, a date confirmed in Microsoft 365 roadmap 59438. The EHLO blog announcing the commencement of the deployment confirmed that tenants should see the new feature by mid-March.

Important Points About Message Recall

The important points about message recall for Exchange Online are:

• The implementation uses an Message Recall agent (a background process) that processes special recall messages (of the IPM.Outlook.Recall class) sent from Outlook for Windows to all message recipients. When enabled for a tenant, the existing recall message UI in Outlook (Figure 1) invokes the new feature instead of the old. No other client can recall messages for now, but Microsoft says that they’re working on an API that will allow other clients to recall messages.
• The agent steps in when it sees the special messages in the stream passing through the Exchange transport system and processes the recall instruction against recipient mailboxes. Apart from the need to recall a message from Outlook for Windows, no other client dependency exists. After the agent recalls a message, client synchronization makes sure that recalled messages disappear from user view. It doesn’t matter if a message has attachments or if it is protected with a sensitivity label or other encryption.
• The agent uses message identifiers to allow it to recall messages even after the recipient has moved them from the inbox.
• The message sender receives a message recall report after the agent finishes processing. The report summarizes the successful and failed attempts to recall the message. Typically, the recall report arrives within a minute or so after submission if the agent needs to deal with ten or so recipients. The more recipients, the longer it takes for the agent to collate the recall status for all recipients. Microsoft says that it could take five minutes for a summary report covering “a few hundred recipients.” Receiving this kind of confirmation should reassure people who recall messages that the process worked. However, even a successful recall is no guarantee that the recipient has not read, printed, or otherwise dealt with the message before its recall.
• Users can recall messages months after their original sending. Although the extended period means that more recipients are likely to have read the content, recall still removes the copy of the message from their mailboxes.
• Because a recalled message is effectively a hard delete of the item from user mailboxes, Exchange Online captures copies of messages recalled by the agent for mailboxes subject to retention or litigation holds to make the messages available for eDiscovery
• The Message Recall agent can only process messages delivered to recipients within the same organization. A message cannot be recalled if leaves the organization and goes to another Exchange Online organization, Exchange Server, or another email system. Microsoft has the technical capability to recall messages sent to any Exchange Online organization and to Outlook.com recipients but cites legal and privacy reasons for restricting recall to the sender’s organization.
• The Message Recall agent only works for Exchange Online. There’s no equivalent for Exchange on-premises servers.
• Messages from shared mailboxes can be recalled. However, the summary report is inaccessible. Microsoft is aware of the issue and is working on a fix.
• If organizations don’t want users to be able to recall read messages, they can update their organization configuration by running the Set-OrganizationConfig cmdlet to update the RecallReadMessagesEnabled setting. By default, the setting is null and the feature works. To disable message recall for messages that recipients have already read, run:

Set-OrganizationConfig -RecallReadMessagesEnabled $False

The setting affects all mailboxes in the tenant. You can’t enable message recall for selected mailboxes. The setting can also be changed through the Settings section of the Exchange admin center (Figure 2).

If you want to disable message recall completely, run Set-OrganizationConfig to update the MessageRecallEnabled setting:

Set-OrganizationConfig -MessageRecallEnabled $False

Overall, Microsoft estimates the improvements they have made allows message recall to have a 90% success rate. Your mileage will vary depending on the recipients of the messages that you attempt to recall. Obviously, if the majority of your email traffic is external, your success rate will be lower. This might be a factor in tenants where Teams is the preferred choice for internal communications and email is largely reserved for external communications.

Message Recall Helps People

Over my 27 years working with Exchange, I haven’t used message recall more than once or twice. The Microsoft data indicates that I might be unusual. It seems like many people find the need to recall a message and are subsequently disappointed. Let’s hope that the new message recall brings more happiness to those who need it after they make a mistake sending a message that they really wished they hadn’t.

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