|I rewrote the function so that I can do this for other things in the future. The same function now serves both combat and party invitations.
So when you ignore an invitation, it pretends to delete the message and decreases your inbox amount. At the same time it sends a poke to the server to delete that message. The next time the page is reloaded, that message doesn't get loaded from the server (as it doesn't exist any more). It's kind of interesting that the message exists in a ghostly, invisible form after it stops having corporeal form.
You can go in and make it visible if you want. Try a $("#partyInvite5").toggle() or something. Oh, you need to know the party number. Good luck.|