This article describes some of the reasons that out-of-office will not function as expected.

Did not set it up correctly

Ensure that you have followed these instructions, Setting the Out of Office Auto Reply for Gmail and Exchange Online.

Email not received

In general

Problem: Email is being received, but it being sent to the Junk or Spam folders

Solution: Train your mailbox to recognize the mail as legitimate and to not place it in the Junk or Spam folders.

From a Google-Backed shared mailbox (PACE) account

Problem: Our dual mail routing setup (Google and M365) and the shared mailbox being backed by a Google Group.

This works for internal addresses because it never leaves the environment. However, if you are sending to external addresses, it will hit the Google Group first and the Google Group isn't processing the auto replies properly. Therefore, you will need to set up an auto reply on the Google Group itself as well.

Solution: Here are the steps to set the auto reply on the google group:

1. Find your Google Group in question at https://groups.google.com
2. Select your group
3. Select Group Settings
4. Select Email Options
5. Scroll and fine the Auto Replies selection
6. Select one or more of the appropriate options and provide the necessary language for each auto reply selected:
   • Enable auto-reply to members inside the organization
   • Enable auto-reply to non-members inside the organization
   • Enable auto-reply to members outside the organization
   • Enable auto-reply to non-members outside the organization
7. Click Save Changes at the bottom