Wanted: Most secure unencrypted email solution

Dear lazy web,

Thanks to the global surveillance disclosures, I am searching for a secure email solution. Using end-to-end encryption seems to be the only secure solution to keep the email content private, but it does not protect your email header. End-to-end encryption has the big drawback that the communication partner has to use it, which is rarely the case. I want to communicate as secure as possible even with people that do not use end-to-end encryption. What is the most secure unencrypted email solution?

Should I rent a (virtual) server in my country (Germany) and run my own email server on it? Do you know any reliable, inexpensive server host for such use case?