A lot of companies use Office 365, including Exchange Online, instead of on-premises Exchange. For many organizations, the decision is more about what they don't get from Office 365, instead of what they do get. I run my company's email in Office 365. Because I don't want to manage my own Exchange deployment, Office 365 is the best decision. For the sake of convenience, I'm willing to give up control of infrastructure decisions.
One of the primary advantages of Exchange Online is a highly available messaging option with a strong service-level agreement. The equivalent on-premises infrastructure could be cost-prohibitive and a logistical headache for a small- or medium-sized business. There's also the immediacy of Office 365. It's as close as admins are going to get to snapping their fingers and having Exchange 2013 deployed. From an ongoing maintenance perspective, admins will always have the latest version of the product, the latest updates and newest features.
Arguably the best feature of Office 365 is that it supports hybrid configurations with on-premises deployments of Exchange Server. Fundamentally, it doesn't have to be a "one or the other" decision because the limitations of one can be fortified by the strengths of the other. But the reality is that organizations don't want to move all or even part of their messaging system to the cloud for a number of reasons. For these organizations, the on-premises deployments of Exchange 2013 will provide the same functionality as Exchange Online without the potential limitations of a shared infrastructure.
My recommendation is to carefully review the service descriptions Microsoft published for Office 365. If admins find anything in the service description that's a deal breaker for their organizations, it's better to find out before beginning a migration to the cloud. Even if admins find a stopgap, a hybrid option could be the right answer for an organization.
About the author:
Richard Luckett is a consultant and instructor specializing in messaging and unified communications. He's been a certified professional with Microsoft since 1996 and has 20 years of experience in the public and private sectors. He's a Microsoft Certified Trainer with more than 15 years of training experience with the Microsoft product line and received the Exchange MVP award in 2006, 2007 and 2008. He's also an expert in deplo ying and integrating Exchange Server and Lync Server. He leads the Microsoft training and consulting practice at LITSG.
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