Jan 11 2011
Peak Email
I used a free Chrome Extension, Graph Your Inbox, to plot my inbound and outbound GMail volume by month since I first joined in late 2004. As far as I can tell, this is counting conversation threads and not individual emails.
It looks like I reached peak inbound email around March '09. I attribute the decline since then to several things: aggressive email filters, increased usage of Twitter and Chatter, and an unfortunate proliferation in the number of email addresses I maintain.
Less email is good. My condolences to those of you with inboxes spiraling out of control.

