[estro]

What's to stop someone from sending sensitive data as an attachment via email using an encrypted email service? I don't think a proxy can detect much besides data size correct? I suppose a virtual desktop could log which files are uploaded.

[dzhiurgis]

Most email servers reject that (I tried to send something to a Deloitte consultant and gave up after password protecting ZIP file).

While most of such companies actively MITM their HTTPS connections (I wonder whether Google does that - theoretically they are CA so it would be extra easy for them), you could probably get away to uploading said file to any service that is small enough to be unknown to corporate firewall providers (Symantec, etc).