Do you receive email with a mystery "J" or "L" in them?

Fabulous! Thanks very much Mike J

What the heck are they? It's actually not much of a mystery: they are automatic emoticons inserted by MS-Outlook when someone types :-) or variants.

Outlook substitutes the string for the letter J or L, and formats that character with Windings, which in that font maps to the smiley or the frowny glyph.

I guess if you look at J and L sideways, and pretend only half their mouth is working, it kinda makes sense for a J to be a smile and an L to be a frown...?

Well, anyway, now you know.