User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:53.0) Gecko/20100101 Firefox/53.0 Build ID: 20170413192749 Steps to reproduce: DCR: Allow users to lock attachments by type to prevent opening Actual results: Latest phishing scam relies on a Google doc to be opened by the user; it grabs contacts and spreads itself to them. E-mail address may look legit, but it is spam, generated by the Google doc phish. wired.com/2017/05/dont-open-google-doc-unless-youre-positive-legit/ Expected results: Allowing users to lock attachments ('lock .pdf; lock .[whatever Google docs are], lock .docx, etc.) by type allows this sort of attack to be prevented to some extent. Allowing individual doc unlock (unlock this doc? y/n) would be nice. Do-ability? not sure, but this would be nice.