In EU private messages are protected, companies can't just read through your entire mailbox as you have a reasonable expectation of privacy. Of course they can

In EU private messages are protected, companies can't just read through your entire mailbox as you have a reasonable expectation of privacy. Of course they can read it if they have a good reason: e.g. you're leaking information to the competitor, but you can't just read random emails between an employee and their spouse for no reason. (Article 8 ECHR).