In Outlook enable the Developer option on the ribbon under File > Options > Customize Ribbon. Check Developer in the right column.
From the Developer tab select Design a Form
Pick message and open.
Select the Actions tab, then select the line with Reply to All and click Properties.
Uncheck the Enabled box in the top right then select OK.
Select the Properties tab, then check the Send form definition with item box. Choose OK on the dialog box that appears.
If this gives an error click Properties again
Click Publish > Publish Form As…
Save it in your personal forms library as something easy to remember like NoReplyAll
Close the windows
Click on Developer tab > Choose Form > Look in: Personal Forms Library > NoReplyAll > Open
Then send that message to AllCorp1 or as many people as you want and they will see…