Courtesy of Daniel:
That was a while ago but they've started sending poorly disguised spam in the form of "notification" emails. Here's the one I received:
Hello Daniel, I've received your message entitled "Re: [Open Manufacturing] Re: DIYBio: Oranges without the tree?". I wanted to let you know that I've added you to my Boxbe Guest List. Boxbe helps me manage my email by prioritizing messages from people I know. You'd be amazed at how much better my inbox is now. This is the only email you will receive about Boxbe from me and there is no need to respond. Learn more about Boxbe. Thank you, email@example.com About this Notice This courtesy notice is part of a free service to make email more reliable and useful. Boxbe (www.boxbe.com) uses your existing social network and that of your friends to keep your inbox clean and make sure you receive email from people who matter to you. Boxbe Say Goodbye to Email Overload www.boxbe.com Final-Recipient: rfc822; firstname.lastname@example.org Diagnostic-Code: X-Boxbe-Notice; Sender not pre-approved, delivery likely delayed. Follow instructions in above notice Status: 4.7.0
The bit about "to keep your inbox clean and make sure you receive email from people who matter to you" is particularly ironic.