The following article provides step by step instructions on how to add an Out of Office reply using Outlook Web App.
1. Log into Outlook Web App: https://mail.secureowaonline.com
2. In the upper right hand corner, select Options > Select Set Automatic Replies.
3. By default the automatic reply is disabled. To enable select the radial button next to Send Automatic Replies.
4. The option to, "send reply messages to users not in your network" by default is disabled. Create a message you wish outside senders to receive.