Apple ID asks for old email address password
This only seems to happen when I install updates. When the Mac restarts, the app store opens and I'm logged in with my current email address, but a window pops up asking me to login with an old email...
I have ignored and thought I might find a reference to that old email address within my Apple ID account, but I can't find any reference to it... There's something on my computer still hanging onto it though..
Any ideas how to get rid of this?
MacBook Pro with Retina display, macOS High Sierra (10.13.1)