if you die in a dungeon and you have some valuable items you don't wanna lose or you don't wanna repeat the whole process of getting there again, you ask to be rescued. You send a SOS mail (password), which is the ones you see posted here.. the rescuers in turn input the password so that they can get access to the rescue mission. The mission takes place in the very same dungeon where the rescuees die. you have go to the floor where they fainted, fight off hordes of pokemons (monster house) and find the rescue spot. Once this is done, you can exit the dungeon and send an A-OK letter (password), which is the ones you see the rescuers post (such as me and Orc). The recuees in turn input the A-ok the confirm that they've been rescued, they can choose to send a Thank you letter later on that may contain the payment for the rescue (an item).
Anywho... This sucks... i just died on the 65th floor of the Ruins and i had a lot of important items with me.. knowing that no one's probably gotten that far, i just had to reset my game since it's a hopeless case..
It sucks when you're too far and no one's there to rescue you.. =\ Mind you, my Level 40 team got pwned by a rhyhorn wtf.