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what does DNO mean?

and yes, you have to explain nrn the first time, hence this post

Do Not Open. It was/is used for simple time saving communication.

Example: Will be late for the 2pm meeting. *DNO

The above would be in the email title, all the info is said right there, the receiver did not need to waste time opening a blank email. This was supposed to be common knowledge in offices. Inevitably the email gets opened and the receiver is confused, even if they'd been told about it. But if they were told about it but didn't see it for a time and had forgotten by the time they saw it, they'd be curious to know what DNO meant lol.

Obviously there are people who did get it and use it. I was simply reminded of it when I read your post. Very similar and potentially beneficial concept.

I learned nrn from a very busy, and a VERY successful person

Whoa, I feel I may have offended you and that was not my intent. I am not trying to say it won't/doesn't work, was just sharing experience with something similar. Apologies if you are offended.

I am not a scary guy, I promise

hahaha, no worries, I'm not either ;)

not at all, good sir. we are clear :-) I was just letting you know that part