Is it possible to add a button to the end of the message, that will delete the message? So that a user can get ridd of the messege after he has read it....
.... and maybe a second thing like "automatically delete message, if message is older than x days"... so the function to display the message checks the date of the message and erases it if older than x days...
Cause it will get hard to keep track of all messages as an admin... and this all will make sure the users don't see some obsulete stuff for too long....