be careful with word properly. I bet that for many things imap works by standars. Problem might be that servers imap do not work by standards. I know that end users should not give rats *** about definitions or how something really works. Just vote by selling and then buying stuff that fulfills their need.

imap subscription is probably handled by server side. Do not ask. Google here.

Imho modest is nice example of software that should not have been installed at all as default software. It's just basic example app that shows emails are possible on this device.