Make "Reply all" your default setting
- On your computer, go to Gmail.
- In the top right, click Settings .
- Click Settings.
- In the "Default reply behavior" section, select Reply all.
You can still choose to reply to just one person, but "Reply to all" will be the first option.
A method that works for both Office 365 and Exchange 2016 On-Premises is to go via the Options screen.
- Click on the Gear icon in the top-right corner left from your user picture.
- From the menu that open choose:Exchange 2016 On-PremisesOptionsOffice 365section: My app settings-> Mail
- In the left pane choose: Mail-> Automatic processing-> Reply settings
- Set your default response to: Reply.
- Press the Save button at the top.
- Click on “Options” in the top left corner to return to your mailbox.
Setting the default Reply action via the Options screen.