How to adjust margins in Mail?

If those options ever existed, it would have been a very long time ago. Looking at Apple's page of settings, there is no such thing from High Sierra and forward.

Format text in emails in Mail on Mac - Apple Support

The closest you can get to any type of margin is to type out your email as normal. When you're done, do a select all of your copy, then go to the menu bar and choose Format > Indentation > Increase.

Or, from the tool bar, click on the Indent icon and choose Indent.

Mail does one preset left indent spacing. That's it. Choosing Outdent from either menu simply removes the applied indent.

WATSONN11 wrote:

3. Click on the "Fonts & Colors" tab.

4. Click on the "Set..." button next to the "Message font" option.

5. In the Fonts window that appears, click on the "Show" drop-down menu and select "Settings".

6. In the Settings window, click on the "Margins & Tabs" tab.

7. Adjust the margins as desired by entering values in the "Left", "Right", "Top", and "Bottom" fields.

I don't 'see any of these options. There is no "Settings" in the Fonts window anywhere that I can see.

HY! FIRST OF ALL THANKS TO DISCUSS THIS QUETION IN THIS BEST APPLE COMMUNITY I HOP MY ANSWER WOULD HELP YOU.

To adjust margins in Mail on a Mac:

1. Open the Mail app on your Mac.
2. Click on "Mail" in the menu bar and select "Preferences".
3. Click on the "Fonts & Colors" tab.
4. Click on the "Set..." button next to the "Message font" option.
5. In the Fonts window that appears, click on the "Show" drop-down menu and select "Settings".
6. In the Settings window, click on the "Margins & Tabs" tab.
7. Adjust the margins as desired by entering values in the "Left", "Right", "Top", and "Bottom" fields.
8. Click "OK" to save the changes and close the Fonts window.
9. Click "OK" to save the changes and close the Preferences window.

Your margins in Mail should now be adjusted according to the values you entered.

You don't. Mail is not a word processor.

Thanks for letting me know I didn't completely miss something.