I'm wondering this myself. Melanie, did you end up testing using emoticons in subject lines?
Hi Nicole
I suggest you can use emoticons as text symbol.
You can copy them from here - http://text-symbols.com/ or http://collarme.forumotion.com/t16-letters-numbers-and-symbols
Currently, they are properly supported in Hotmail, Gmail and Yahoo.
Also, I suggest not to use more than 1-2 emoticons in the subject line as that may affect inbox delivery for the campaign.
Regards
Alok