Ok so basically I just want to ASK (not request) if it's possible in any illegal way to prevent a person from messaging you on msn, but still appear online to them.
For example:
For the last 2 days, I just can't send a message to a certain contact on my msn because it says:
"The following message could not be delivered to all recipients"

I know it's a common problem, but could a person do that? Or is it just a msn problem?

I really NEED to know, please! Thank you.

You or the person you are trying to message might be using a lot of bandwidth. Try restarting the router or restarting msn or your computer.