Stop Apple's Mail App From Opening Browser Email Links in One Quick Step
Summary: In MacOS, clicking an email or “mailto” link in whatever browser you’re using automatically opens Apple Mail, the default email application. Stack Exchange user Randy Marsh suggests a quick settings change to stop Mail from inadvertently launching. To fix the auto-opening issue, open the Mail app, select Mail in the menu bar, and head to Preferences. You can also use the “⌘+,” shortcut.