[SaintSal]

tl'dr; A couple of months back I posted an article about Gmail retention (see here) in which I showed that Google not only saves copies of your unsent messages, but virtually every iteration of any message you type is potentially saved by Google. This means that it is available by subpoena to Google from whichever entity sees fit.. [With Meilvelope] Yes, your email message is encrypted. Yes, anyone attempting to intercept the message won’t be able to read it while either in transit or looking in your sent folder. Yes, this makes you feel warm and fuzzy because you’re using encryption until you understand that, yes, Google still has the pre-encrypted message sitting on their servers. Not only this, but they saved multiple copies while you were typing your message.

[seanieb]

Mailvelope developers are aware of this, the default is to compose emails in separate window, and not on Gmail.

https://www.dropbox.com/s/ffidxl4u4dylsp8/Screenshot%202014-...