No, if he’s not in IT it should not be possible - I don’t know what email system you’re using but this person should not have the access you’re saying they do.
I’m not saying it shouldn’t be technically possible (I’m a sysadmin, I know what’s possible in a corporate environment), I’m saying your organization should not make it possible.
If he’s in some leadership position I’d be looking for other employment and/or reporting that person to your corporate compliance officer if you have one.