How to Set Out of Office in Outlook App?

Mobile app (iOS/Android), step by step

1. Open the Outlook app and tap your profile picture (top left).
2. Tap the gear/Settings icon.
3. Select the account you want to set the reply for (if you have more than one connected).
4. Tap Automatic Replies.
5. Toggle it on, write your message, and optionally set a start and end date/time so it turns off automatically.
6. Save.

Desktop app (Windows/Mac)

1. Click File.
2. Select Automatic Replies (Out of Office).
3. Choose Send automatic replies, set the date range, and write the message.
4. Optionally write a different message for people outside your organization under the "Outside My Organization" tab.

Outlook on the web (outlook.com or Office 365 web)

1. Click the gear icon (Settings).
2. Search for or navigate to Automatic replies.
3. Turn it on, set dates, and enter the message text.

Internal vs. external messages — why this distinction exists: Outlook lets you send a different automatic reply to people inside your organization (who might get more detail, like who's covering while you're out) versus people outside it (often a shorter, more general message, since external senders don't need internal coverage details).

A note if the mobile app doesn't show an Automatic Replies option: this setting is tied to the Exchange/Microsoft 365 account type — it may not appear for some personal (non-work/school) Outlook.com accounts on certain app versions, in which case setting it through the desktop or web version of Outlook is the more reliable route.

The closest sibling pages are How to Silence Unknown Callers? and How to Split Screen on a Chromebook?.

See other Phones, Computers & Devices questions for other answers in this topic, or start from more researched answers.