Hello dieter. behrands,

I hope this will help you.

To set your own default font for composing new messages in Mozilla Thunderbird:

Make sure each account is set to composing with HTML formatting Select Tools > Options (or Thunderbird > Preferences... on a Mac) from the menu in Mozilla Thunderbird Go to the Composition category Make sure the General tab is selected Choose the desired font, font size, and colors under HTML Click Send Options...

Make sure either Ask me what to do, Send the message in HTML anyway or Send the message in both plain text and HTML is selected under When sending messages in HTML [...].

Click OK Close the configuration dialog

Hii

To set your own default font for composing new messages in Mozilla Thunderbird:

   Make sure each account is set to composing with HTML formatting
   Select Tools > Options (or Thunderbird > Preferences... on a Mac) from the menu in Mozilla Thunderbird
   Go to the Composition category
   Make sure the General tab is selected
   Choose the desired font, font size, and colors under HTML
   Click Send Options...