In Outlook on the web (Office 365 business), delayed-send messages are not stored in an Outbox folder. They sit in Drafts until the scheduled send time.
To locate and cancel the scheduled message:
- Sign in to Outlook on the web.
- Open the Drafts folder.
- Look for the message that was scheduled with Send later (subject and recipient should match what was scheduled).
- Open the draft and either:
- Delete it to cancel sending, or
- Edit it and send immediately if desired.
If the message is no longer in Drafts, it has either already been sent (check Sent Items) or deleted.
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