I’ve seen both NM and NVM used to mean Never Mind. I’ve never seen NM used to mean No Message.
Now that I think about it, I do remember seeing nvm sometimes. But nm was never “no message”, to me.
In my non authoritative mind, NM = never mind. It could be n/m too. Nvm is same.
NT or n/t = no text. eom = end of message
Ohhh, that’s very different
Y’all missed the smiley, right? Here’s a cite anyway. 
OH thank you!!! Sorry about that, I’m super new here!
Low-brow posters, that’s who resorts to such desperation. Take 20 seconds and review your damn message before posting! :rolleyes:
In my case, it usually happens if, while preparing my message, it gets ninja’d by someone else’s post.
In my experience, it’s usually the high quality users that routinely use the “nm” approach. Don’t you agree? 
The acceptable response to that is "Ninja’d by [username]!
Optionally followed by a disparaging joke about typing/searching speed.
The question has been asked and answered in this thread and in PM, so I’m locking this thread.