In English, "Instant messaging" can be abbreviated to IM. The equivalent words in French are either "Messagerie instantanée" or "Clavardage" (chat). Would it be appropriate to abbreviate "Messagerie instantanée" to "MI"?
Update:
Upon further research, I'm seeing two places use the abbreviation "MI":
- Fido (you may have to switch the language based on location)
- Yahoo! Messenger
Still, the phrase "Messenger" or "Messagerie instantanée" appear on those pages, giving the abbreviation context.