The Mailbox glitch, as noted on from LoadComplete's Crusaders Quest, was infamous for being one of the worst MMO glitches to screw over players. Today, this glitch is regarded as one of the worst MMORPG glitches ever in history.
The Mailbox glitch required players to get all mail by clicking on the button several times. This however, resulted in ban waves that consisted of around several dozen but unaware players... (since the glitch allowed players to exploit the mailbox via grabbing multiple items again that were already removed from the mailbox)
Demonstration: Player has A in the mailbox, but if Player presses "get all" twice rather than once, it for some reason dupes A x2 in the Player's inventory, showing two A's in the inventory.
Why It Sucked
- Many people were unaware of the presence of the glitch itself, leading to many players who were not intending to exploit the glitch getting ban-waved, which would later get spread via players on Reddit or the Discord itself.
- The developers didn't have the glitch at all compared to the player's version (Whether or not the developer's version of CQ is different is unknown. This is what you have beta-testers for.)
- Instead of trying to warn players about the glitch, LoadComplete went on to shrug it off and continue ban-waving players that exploited the glitch out of awareness.
- LoadComplete did a bad job of telling the glitch itself when they patched it "issue with the mailbox where your received mail is not displaying to the user." as stated in the patch notes. This was NOT the actual problem; the problem is that the mailbox was giving out clones to the player, NOT refusing to deliver them.
- This therefore, caused a downfall on the game Crusaders Quest itself, and left a mark on the game itself after losing many players thanks to the mailbox glitch.