Last I checked in June, Zimbra, Yahoo's open-source e-mail and calendar software, . 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. 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?