I honestly don't use Outlook myself much. But here's what GPT has to say about it:

To change the default font size in Outlook 2024 and ensure that emails sent from Microsoft Access use Aptos size 10, follow these steps:

1. Change the Default Font in Outlook

Even though you modified the Normal template, Outlook may still override it. Set the default font manually:

For New and Reply Emails

1. Open Outlook.
2. Click File > Options.
3. Go to Mail and click Stationery and Fonts.
4. Under New mail messages, click Font and choose:
   - Font: Aptos
   - Size: 10
5. Repeat the same under Replying or forwarding messages.
6. Click OK to save.

2. Force Access to Use Size 10 When Sending Emails

If you are sending emails using Access VBA, Outlook might reset the font size to 12. To enforce size 10, modify the HTMLBody property.

Modify the HTML Formatting in VBA

If you are using Access VBA to send emails, adjust your `HTMLBody` to enforce Aptos size 10 explicitly:

Code

Dim olApp As Object
Dim olMail As Object

Set olApp = CreateObject("Outlook.Application")
Set olMail = olApp.CreateItem(0)

With olMail
    .To = "[email protected]"
    .Subject = "Test Email"
    .HTMLBody = "

This is a test email from Access.

"
    .Display 'or .Send
End With

Set olMail = Nothing
Set olApp = Nothing
Copy

3. Adjust Incoming Email Font Size

If received emails are appearing in size 12, Outlook might be zooming in. Try these fixes:

- Change Zoom Level (Temporary)
  - Open an email.
  - Press Ctrl + Mouse Scroll Down to decrease the zoom.

- Change Zoom Level Permanently
  - Open an email.
  - Click Zoom (bottom right or from the Ribbon under the Message tab).
  - Set Zoom to: 100%.
  - Check Remember my preference and click OK.

This should ensure that both outgoing and incoming emails use Aptos size 10 instead of 12. Let me know if you need any refinements.