Excerpt from this article on email sign-offs:
“XOXO”: Contrary to popular belief, this does not mean “hugs and kisses.” If anything, it’s intended to convey light affection, like a pat on the butt from a Texan aunt. You shouldn’t take it as anything more.
“XOX”: This indicates full, throbbing, sexual desire. The person who signs off this way is hoping that you’ll picture her naked silhouette playing the saxophone in some mist.
“XO”: This is like when you lean in to kiss your Texan aunt on the cheek but you both turn the wrong way and kiss on the mouth.
“X”: This is a simple, respectful nod, indicating that everything is going absolutely fine.
“Thanks”: This is completely sarcastic.
“Sincerely”: This is the way Abraham Lincoln always signed off, so take that for what it’s worth.
“Peace out!”: This person probably has an earring in the shape of a turtle, and tries to get everyone to notice it.