Not being able to read dead employee's emails seems like a really tiny inconvenience (especially since there are so many ways an employee can effectively delete mails that you're doing something catastrophically wrong if your business continuity is dependant upon a mail account access) in comparison of constant monitoring of peoples private communication.
And "we may need to occasionally access your account on company-run email servers" is also a really different thing in contrast with "constant monitoring of peoples private communication". I doubt any company really gets a positive ROI on constantly monitoring people's chats, so it's their loss. I think other commenters have made a sufficiently good case for your work email not being considered private communication anyway.
I mean, you're also doing something catastrophically wrong personally if your privacy is dependent on a company wanting to read company-related data on their own infrastructure but thinking, "Oh, no... a European court might frown on this..."
