I knew about the audit route, and I should add that at least for this method, the fact that you accessed the e-mails is permanently saved in the audit records.

I knew about the audit route, and I should add that at least for this method, the fact that you accessed the e-mails is permanently saved in the audit records. While this means that yes, "the company" can read your e-mails, it also means that they can't deny doing it if it actually happened. Neither can a rogue employee do it without there being a record, assuming you have accounts properly setup and don't share account passwords.