This article explains how to select multiple messages in Mac Mail. Instructions apply to macOS 10.15 (Catalina) through 10.7 (Lion).

Your Apple Mail account can quickly get out of hand if you don’t read, sort, filter, delete, save, or print some of your emails in an effort to stay on top of your correspondence. You can process one email at a time, but your productivity improves exponentially when you process multiple emails at once.

You can collect a series or combination of messages in the Mac Mail application in several ways. For example, you can forward multiple messages at once, save them to a file, send some to the printer, or quickly delete them.

Open the Mail application on your Mac by clicking the Mail icon in the Dock.