Xapo can not be used to sign a message, on top of that there is no standart way to verify a signature for a multi sig address. Posting this address here does nothing for you, but increase your post count by 1.

Posting it here is step 1.  The idea is that if your account was hacked or stolen, you could then sign a message from this address which you posted in order to prove that you were the original owner.  If you can't sign a message from the address, then you'll never be able to use the address for account recovery, which is sorta the point.

Quoted for you for future reference, a signed message is always better, good luck.

It's already quoted, As M.Zakir said a single quote is enough.

Quoted, you're safe now.. with sign meesage will be better.

quoted.

Quoted! For future reference, you'd be better off signing a post here with this address (how to do this depends on the client/wallet you use) and posting here - if you ever lose control of your account here you'll need to sign something with this address to prove you control it).