SAFARI BROWER
To make Safari use mailto links, set your default email application on macOS via the Apple Mail app settings or install browser extensions for webmail services like Gmail. On macOS, go to Mail > Settings > General and change the "Default email reader". On iOS, change the default app in Settings > Mail > Default Mail App.
iOS (iPhone/iPad Safari)
Go to Settings > Mail (or settings for your specific browser app like Chrome/Firefox) and select the "Default Mail App".
If the app you want to use is not listed, you must download it from the App Store first, as Safari inherits the system-wide default app.
If mailto links do not work, ensure an email account is actively set up in the Apple Mail app.
On iOS, if an email app fails to open, it may not support the mailto protocol, requiring a switch to a different app.