What I find most frustrating when it comes to GPG encryption and email is the lack of support for public key encryption for generated mails. I've seen very few sites supporting GPG and if they did, I found it always just worked and I imaging not much of a big deal to setup. So why do even the biggest shops not offer this? I really would like to be able to upload my public key to e.g. Amazon. It's great to make the checkout process and everything super secure, but just to send every purchase you did and your personal data in an unencrypted mail across the web afterwards.