Earlier this month, Gmail, the popular e-mail service provided by Google, experienced a service outage that left some users without their e-mail for 24 hours. Some of the users who were affected August 15 included customers of Google Apps, Google's software as a service (SaaS) suite that includes Gmail, calendar, documents & spreadsheets, instant messaging and wikis.

The incident begged questions such as: how reliable are online e-mail systems like Gmail? Are they a viable alternative to traditional, on-premise e-mail systems? CIO asked Michael Osterman, president of Osterman Research, who has studied the messaging and communications facets of software, both the installed on-premise variety and SaaS since his company's founding in 2001. Osterman says the Google outage demonstrates the need for Gmail to have an offline mode, but thinks a lot of this is only news because it's happening to the high-profile Google.

Were the Gmail outages a commentary on hosted e-mail from SaaS providers (like Google) or is it something we should have expected?

I think it should be expected. E-mail outages are not uncommon, regardless if the infrastructure is on-premise or hosted. If you were to look at an in-house infrastructure, it also experiences downtime. You don't hear about it as much unless it were a General Motors or a Bank of America or something big like that. If Bank of America's e-mail goes down, they're not going to get on the phone with you and say, "hey, guess what just happened!" They're not necessarily trying to keep it a secret, but they're not trying to make it well known either. The Google Mail outages is given more attention, and it will give SaaS a black eye. But if you look at Google's records, Gmail is still well over 99 percent available.

If e-mail outages are unavoidable, what could Google or other SaaS-based e-mail providers do to help their customers during these periods of downtime?

Part of the problem is a lot of SaaS users (like Gmail users) are just using a Web-based interface. They don't have offline capability. They're even more dependent upon the system being up because as soon as the system goes down, all of their functionality stops. For the typical desktop user, you can still sit in Microsoft Outlook and keep cranking out e-mails that just pile up in your outbox. You can still look for contacts, where as with a completely online model, you can't do that when the system is down. Organizations using SaaS need a mix of offline and online capability. It makes sense for Outlook to work with Google mail or something like that. Zimbra, for instance, has a desktop client you can download from their website. The experiences [between that and the Web-based interface] are very similar, except when the mail goes down. [With Zimbra], you can still do work in the desktop client.