Eudora file with signature:

<html>
<body>
<font size=1 color="#0000FF"><br>
</font><img src="file://C:\xxxxxxxx\sign.gif" width=18 height=18 alt="sign"><font face="Comic Sans MS" color="#0000FF">&nbsp;<b><i>My_name</i></b></font>&nbsp; <img src="file://C:\xxxxxxxx\sign.gif" width=18 height=18 alt="sign"><br></body>
</html>

Thunderbird file with signature

<!DOCTYPE html>
<html>
  <body>
    <img moz-do-not-send="false"
src="data:image/gif;filename=sign.gif;base64,R0lGODlhEgASALMPAFxcXKUAIdPT02aZmf8AAHd3d4SCAP///zMzZmZmmWZmZpmZzGYzM8yZ/8zM/////yH5BAEAAA8ALAAAAAASABIAAAR9kL1Jq32MBTmz59j2IERmNF9jZAQyIVrjOCgj05v73nPD07qHQraYGY3FhmIydCwMhiM0uRTyDojFAnEwKpm/hDZx/FqdxyMVPCOn3eZCsZ2o170FSvR46EorBTwLAgJzNHmANwBaAD2IFgUnAwAAAyqPFw8FCpQKmJmgFhEAOw=="
      alt="sign" width="18" height="18">&nbsp;<font face="Comic Sans MS"><b><font
          color="#0000ff">My_name</font></b></font>&nbsp;<img
      moz-do-not-send="false"
src="data:image/gif;filename=sign.gif;base64,R0lGODlhEgASALMPAFxcXKUAIdPT02aZmf8AAHd3d4SCAP///zMzZmZmmWZmZpmZzGYzM8yZ/8zM/////yH5BAEAAA8ALAAAAAASABIAAAR9kL1Jq32MBTmz59j2IERmNF9jZAQyIVrjOCgj05v73nPD07qHQraYGY3FhmIydCwMhiM0uRTyDojFAnEwKpm/hDZx/FqdxyMVPCOn3eZCsZ2o170FSvR46EorBTwLAgJzNHmANwBaAD2IFgUnAwAAAyqPFw8FCpQKmJmgFhEAOw=="
      alt="sign" width="18" height="18">
  </body>
</html>