Given that it’s required to sign up for online billing and most online services, I think your younger coworker either doesn’t understand how to set it up on his/her phone or was just straight up lying because the email address was embarrassing or some other reason to hide it.
I rarely check my personal email because of the volume of spam and other noise I receive, so if a friend tried to contact me that way I probably wouldn't get it. I don't set up email notifications on my phone for that reason.
