Choosing fonts

I'm using TBird 31.4 I have chosen Unicode TF 8 and Comic Sans MS as my font for outgoing emails. I send in HTML format. When I choose "write" to create a message the window shows Comic Sans as the body text but it does not show as Comic Sans when i write nor does the recipient receive it in Comic Sans when I send the message. It looks like calibri or Aerial. If i select "options" then Composition or Display it shows the font to be Comic Sans as well. i tried changing to Western but it made no difference and caused other problems such as strange characters appearing in the body of text so i need to use TF 8. Thoughts? Thanks.