Microsoft Outlook supports the use of inline comments to indicate changes you make to the body of forwarded or replied to emails. Although this feature is turned off by default, when it is turned on, your name appears in bold, italics, and in square brackets before the inserted text. This name tag is not applied to text you type at the top of the message that appears before the material you forward or reply to.

To prevent Outlook 2019, 2016, 2013, and 2010 from highlighting changes to the original message when forwarding, do the following:

Go to File and select Options.

In the Outlook Options dialog box, select Email.