What does "protect messages" mean?

Whenever somebody sends youa message on PSN, it gives you an option to "protect" the message. I recieved a message from a friend and accidentally protected it. I then un-protected since I didn't know what it meant. So what does it do? If I protect or un-protect a message, will it send a notification to my friend telling them about it? I'm not sure what it means.

If you protect a message and lets say you decide to hit the "delete all messages" button, the protected message will not be deleted but all of the unprotected messages will be.

If you protect a message and lets say you decide to hit the "delete all messages" button, the protected message will not be deleted but all of the unprotected messages will be.

NamelessJay

I'm not sure if they get auto deleted. I always delete them after I read them. I have a MAJOR organization problem haha. Everything always has to be neat, clean, full, or empty depending on what the situation is.