How many times do people have to say this: There is no such thing as secure email. Assume everything is being read. You can't bolt security on (SSL, mailbox encryption, PKI). You have to design it in from the start. SMTP/IMAP etc have crudely hacked on TLS implementations which aren't even guaranteed to be operational site to site. PGP is just an encapsulation which is rarely used. It's a mess. This is just a repacka…
Okay, Harry, let us know when you're done with that :-) I suspect most of the rest of us would prefer the perfect not be an enemy of the good.
If there is only a small flaw in an encryption system, be assured that it will be exploited to break down the whole system. A simple example are all the issues with random number generators producing not perfectly random numbers; yes, it is just a slight problem in an otherwise good solution but that problem completely debases the overall system.