11x EasyMail\EasyMail.lua:1437: Usage: PlaySound(soundKitID, optional["SFX","Music","Ambience", "Dialog" or "Master"], [forceNoDuplicates, runFinishCallback])
[C]: in function `PlaySound'
EasyMail\EasyMail.lua:1437: in function `CheckAll'
[string "*:OnClick"]:1: in function <[string "*:OnClick"]:1>
(*temporary) = "igMainMenuOptionCheckBoxOn"
Blizzard altered PlaySound. In my copy I replaced all 7 occurrences of PlaySound(whatever text is here); in EasyMail.lua with PlaySound(852); just to get rid of the error. It's not the sound that it was using, but it's a sound that isn't annoying and doesn't bug out the addon.