You can't get banned for this, you're not doing anything against the TOS or EULA.
You can possibly get a temporary suspension if the GM finds you particularly obnoxious but even then I doubt it. Like I said, no rules are being broken.
I've asked GMs about this many times before I did it, they say "Emotes are Orange while system text is yellow" and is just as bannable as someone say ing /em pickpockets you for 5g.