Stationery is an add-on to Mozilla Thunderbird email client that gives you the possibility to create email templates with background images, custom fonts and so on.

Here is a basic template – Arial, black on white, that’s also a workaround for bug 250539 – see comment 163:

<!DOCTYPE html>
<body style="background:#FFFFFF; color:#000000;">
<div id="content" style="font-family:Arial,Helvetica,sans-serif; font-size:11px;">
  <span id="_AthCaret"><!-- initial cursor placement --></span>

It’s HTML5, however, most email clients don’t care about HTML Doctype at all.
I’ve always had problems placing the caret in connection with the caret positioning settings of Thunderbird within my earlier Stationery templates. The <span id="_AthCaret"> element solves this and will be replaced by your inputs.

For more sophisticated email templates look at