how to recall an already sent email

Hi @MCLEISH, Lisa,

Thank you for reaching out Microsoft Q&A!

Based on this reference: Recall an Outlook email message - Microsoft Support ,Please note that message recall is available only if both you and the recipient have a Microsoft 365 work or school email account in the same organization. Messages sent to or from a Hotmail, Gmail, or live.com account can't be recalled.

And here is step by step to recall a message in Outlook for business on the web:

1. Select Sent Items in the left folder pane, then double-click the sent message to open it in a separate window.

2. From the ribbon, select ... > select Recall Message, then select OK in the confirmation dialog box.

3. Shortly thereafter, you'll receive a Message Recall Report in your inbox. Select the link in that message to see whether your recall has succeeded, is pending, or failed.

This reference: Recall an Outlook email message - Microsoft Support also have more details of how to recall in Outlook App version in both Classic and New here:

Note: You can recall a message, but if the recipient has already read it, they will still remember what it said. Therefore, to ensure a successful recall, act quickly.

Hope my information helpful for you, feel free to ask if you need anything else!

Best Regards.

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