Imagine someone sends you an email that needs to be passed along to someone else, but you don’t want to be involved in the conversation anymore. Don't use Forward, as there’s a better way to handle this — Redirect.
Redirect will remove you from the conversation from here on out, so you’re no longer at the whim of everyone else in the chain.
To enable this on the Mac, you need to add a Redirect button to the Mail toolbar. Right-click (or hold the Control key) on the toolbar and click Customize Toolbar. Click and drag the Redirect button into the toolbar. Note that the feature is not available for iPhone or iPad.
For more information, visit Apple Support.