We recently heard from RPost® about a new add-on to its service. The new feature is called SideNote, and seems like a deceptively simple, yet powerful way to improve users' experience when performing everyday email tasks.

Imagine a common email workflow: Alice sends email to Bob and wants to also send a copy to her manager, Carol. Well, that's easy -- every email system allows Alice to CC her manager. But what if Alice wants to include a cover note for Carol to set the message in context, and wants to keep the cover-note private from Bob? Well, there are two ways of doing this:

Alice could send the message to Bob, then dig into her Sent Items folder, find the message and forward it to Carol with the covering text. However, this breaks the semantics of the CC, because now Bob can't see that Carol was included in the conversation. That means that some social cues have been lost, and it prevents Bob's reply going to Carol (unless Alice manually forwards those as well).
The other alternative is for Alice to first send a message to Carol saying "I'm about to send Bob a message and CC you" and include the secret covering text. Then send the actual message, CC'ing Carol.

Either workflow is messy, and causes extra "busy" work, with scope for error. There's a very real cost associated with this loss in productivity. Aren't computers supposed to make this sort of thing easier?

RPost's SideNote allows a sender to add a private note that goes only to the CC recipients of a message. It's modeled after the familiar yellow sticky note, popularized by 3M. All recipients get to know who who got a copy, but only the intended recipients of the private note receive it. Much less messy, less prone to error, and allows users to be more productive.