For setting out of office replies (away messages) in Outlook Web App, please do as follows:

1. Login your Outlook Web App on webpage.

2. Click Settings > Set automatic replies at the upper-right corner. See screenshot:

3. Set the automatic replies for internal senders as follows: (1) check the Send automatic replies option; (2) specify the start time and end time you will enable the automatic replies; and (3) type the content of automatic replies. See screenshot:

4. Go ahead to set the automatic replies for outside senders: (1) check the Send automatic reply messages to senders outside my organization option; (2) check the Send replies to all external senders option; (3) type the content of automatic replies. See screenshot:

5. Click the Save button at the bottom of the webpage.

So far, you have set the automatic replies (out of office) for both internal and external senders successfully in your Outlook Web App.

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