I have an alumni email address from my undergrad university and it clearly states "alumni" within the email address. I list this on my resume and other professional sites.
I had been told in one instance not to use a school email, as I have been out of school for some time and it is less professional.
I have a Gmail account, but is this really deemed more "professional"? Of course if you have a ridiculous Gmail name then that goes without saying do not use that. Assuming that lots of people have similar names, you have a variation of your name or added some numbers.
Would love to hear insight and opinions from hiring managers and recruiters - thank you!