1) Log into your MIT O365 email via outlook.office.com in your favorite browser. Please note the top light blue Outlook bar.
2) Click on the sprocket icon at the top right corner of the light blue Outlook bar. This will bring up your Microsoft 365 Email Settings.
3) Go to "Account" in the left Nav and select on Automatic replies in the center nav column.
4) Go ahead and edit the duration and contents of your automatic replies and remember to save them when you're done.