Why do people out a J at the end of a text or an email?

I thought I had it figured out, and so I went looking to see & I was right. Have you ever typed a smiley :-), and whatever program you were in automatically made it into a smiley? Well, sometimes the code that makes that happen gets lost as it goes through the various email programs and ends up as just a "J" Update for precision:

- Office use MS Word as HTML e-mail editor

- The "smiley" is replaced by a Winding font character.

- The uppercase "J" is a smiley in the Winding character set.

- The "J" will appear each time the text is kept but the font info is lost.