Since I was a master student in (the North American) X university, my email
firstname.lastname@example.org has been still active, even though it is a couple of years that I have left that university. Now, I'm about to finish my Ph.D. in (the European) Y university, and Y will be immediately closing my current
email@example.com upon my graduation. I have heard that writing an unprofessional email address, e.g.,
firstname.lastname@example.org, in the contact information section of an academic CV does not make a good impression on readers. So, I am wondering whether I may use the still-active email of mine corresponding to X in my CV for that purpose. My main concern is two fold: whether or not I am allowed to do that in view of X, and whether or not it is ethically a sound decision because it can mislead readers thinking that I am currently affiliated with X.
PS. My question relatively resembles what are discussed here and here, but the difference is that those questions' contexts are paper affiliation and contacting professors, respectively. However, mine is about the contact information section of a CV.