Last I checked in June, Zimbra, Yahoo's open-source e-mail and calendar software, was at 11 million paid mailboxes. This was a healthy jump from 8 million paid mailboxes in May 2007 and the 4 million paid mailboxes TechCrunch reported back in October 2006.
Well, on Monday The VAR Guy reported there are 20 million paid mailboxes for Zimbra, a massive increase in roughly seven months. It's likely that a big chunk of these came from Zimbra's deal with Comcast. Still, that is amazing momentum.
I mentioned the other day that a significant customer uptake for Zimbra would be much more meaningful than IBM and Microsoft trading customers back and forth. Well, 20 million paid mailboxes spread over 30,000 customers is much more significant than IBM beating its chest over nabbing 5 million mailboxes from Microsoft.
Could Zimbra be the foundation for an enterprise challenge from Yahoo? I wouldn't rule it out.
However, to get there Zimbra/Yahoo has an uphill challenge, as a big percentage of Zimbra's customers fall into the education and small- and medium-size business markets. It's a hard sell to get enterprises to swap out their e-mail systems, and the standard open-source entry point (department-level deployments) doesn't work for e-mail (unless, of course, the customer wants to scale out with Cisco's Linux-based PostPath drop-in Exchange replacement).
Perhaps Yahoo/Zimbra should focus on building PostPath-esque drop-in Exchange integration?