More stuff: the website doesn't work if Javascript is disabled (probably due to the preload and other functionalities). Many consider requiring JS a dangerous possible vulnerability (JS is even disabled by default on Tor). I think every mixer should work without JS or at least have a no-js version.

edit: the Letter of Guarantee isn't working as intended... I just tried a new session which tells me to send my coins to 3426r33JZ23jxBMAJuRLkQJjkEZ1LzAGzi while the Letter says "We hereby confirm that DOMIXER.COM has generated a BITCOIN (BTC) address: 17rCyydfavKR6pHVLDNXA1LAzf8t9at5Jb" (different address).

It also says "to the following address(es):" and then there is no address. I guess it should show the address I want the coins mixed to...?