Office365 How to Update Users Out of Office the Easy Way
If you’ve worked in IT for long enough you will eventually have to deal with a request to update a users out of office. This is usually because the’ve forgotten to do it themselves before going on holiday. In the dark ages it was such a chore, having to find out their password to login as them or assign permissions to your general admin account. No more!
Now its even easier in Office 365, you can now update a users out of office message from the admin portal with ease!
Log into the portal as a tenant administrator

Click and expand the Users menu and click Active users

Click on the user you want to set the out of office on and scroll down to the Mail Settings section.

Expand the Mail Settings and click on Edit to update the out of office messages.

Enable Automatic replies, enter your out of office messages for internal and for external users, check the settings and click Save.

Done!
Summary
Office365 is constantly improving and making our lives as Office 365 administrators easier. Thanks Microsoft!
20th December 2019
Need start and end dates for the Out of Office
2nd January 2020
What role would I need in order to set out of office using the format above?
23rd September 2020
Did you already found out what role is needed?
I have exactly the same question…
21st February 2020
Perfect! I needed this for a CFO that made a typo on her out of office message and she did not have access to change it herself.
20th March 2020
Also would like to be able to post out of office message for only those outside the company without requiring same for those inside. Currently cannot save unless both fields are populated