Email from domain not existing in my cPanel

Good evening community, I have the following problem, when I check the shipping monitor I see that there is an email with the domain "x.com" that sends to the domain "y.com", my doubt is that none of those two domains belongs to me. Since my domain "a.com". Attached link of the screenshot of the error and those two domains that leave my CPanel. prntscr.com/ip3pcz I await your comments, thanks.