I'd like to turn off the feature when Mail automatically capitalizes the next word

To turn off auto-capitalization on your Mac, follow these steps:

1. Open the "System Preferences" app. You can do this by clicking the "System Preferences" icon in the Dock, or by clicking the Apple menu in the top left corner of the screen and selecting "System Preferences" from the drop-down menu.
2. In the System Preferences window, click the "Keyboard" icon.
3. In the Keyboard preferences, click the "Text" tab.
4. Uncheck the box next to "Capitalize words automatically."
5. Close the System Preferences window.

After completing these steps, the auto-capitalization feature will be turned off and words will no longer be automatically capitalized in Mail or other apps on your Mac.

For iPhone:

To turn off auto-capitalization on your iPhone, follow these steps:

1. On your iPhone, tap the "Settings" app.
2. In the Settings app, tap "General," then tap "Keyboard."
3. In the Keyboard settings, tap "Auto-Capitalization" to turn it off.

After completing these steps, the auto-capitalization feature will be turned off and words will no longer be automatically capitalized as you type on your iPhone.