Some e-mail attachments are more sensitive than others, just as some e-mail recipients are more responsible than others. Chrome extension docTrackr lets you encrypt Gmail attachments, set permissions, and remotely destroy them. It also alerts you when a recipient opens or prints an attachment, so you can call shenanigans the next time your flighty friend claims not to have received an attachment.
When docTrackr installs, it adds a button next to the regular attachment button in Gmail's compose window. It also adds a button to the right of Chrome's address bar that provides a link to docTrackr's dashboard. Click on docTrackr's attachment button to select a PDF to encrypt and attach. At present, docTrackr supports only PDFs but states that support for other file formats is coming soon.
When you hit Send on an email with a secure docTrackr attachment, the extension opens a window where you can select access rights. Your choices are: can view, can print, can edit. You can also select an expiration date for accessing the attachment. Click the Secure & Share button to send the e-mail.
On the receiving end, the attachment must be opened using Adobe Reader. I was unable to open a docTrackr using Preview in OS X, for example. Also, for a view-only attachment, the print button in Adobe Reader was grayed out.
You'll receive an e-mail alert when your recipient opens the attachment. You can also view the activity of all the Gmail attachments you sent using docTrackr on its dashboard. And if you forgot to set an expiration date or set one too far in the future, you can click the Disable button on the dashboard for an attachment. There's also an Enable button to reverse course.