Email knits together everyone on the web, and yet there are some things missing from it that can be very useful in a business setting. Verifiable delivery, for example: how do you prove that someone got an email when you said they did? RPost has an answer to that: install their add-in, and their servers will optionally provide signed, verifiable proof of delivery for any email you send with notice to their “registered” service.

They’ve recently added another feature, which could also be useful in business settings: the “SideNote“, which lets you put a little sticky note on emails that is only visible to cc: and bcc: recipients. That’s a nice touch to let recipients know why they got copied on this mail. Pricing starts at 59 cents per unit of use. Unfortunately, at the moment the client side software is Outlook-only.