I spent a little while looking up solutions on adding an automatic reply, or out of office message, to a Shared Mailbox. Unfortunately, I didn’t come across any easy ways to do it via Outlook. Some of them required adding the Shared Mailbox as a separate account, or creating an Outlook rule that has the server reply using a specific message.
Luckily, there’s an extremely easy way to do it via the Outlook Web App. Here’s how it’s done: