Office365 – Migrate and How?


With the advent of Office 365, Microsoft has further strengthened its position as a leading provider of cloud-based services. When compared to the previous Microsoft cloud-based capabilities, Office 365 integrates better with a number of applications including email, user productivity tools, collaborations, instant messaging, and document & project management in a single offering. Being based upon Microsoft Products that were developed with cloud-based and hybrid models in mind, Office 365 is designed to be highly scalable, available and easy to integrate with on-premises systems. With growing popularity of Office 365, more and more organizations are considering migrating to Office 365 as it promises availability of key features and benefits of Exchange Server, Lync Server, and SharePoint Server; without the hassle of time, resource and costs involved with deployment and maintenance of these Enterprise Applications.

The decision to move to Office 365 can have an impact to the organization’s total cost of ownership of Microsoft Messaging environment in the short to medium term. This is due to a prolonged period of managing an additional Microsoft Exchange Infrastructure and its associated technologies along-side the existing Microsoft Exchange Infrastructure – referred to as a co-existence period. During this period the environment can be complex with more Messaging infrastructure components being deployed to support coexistence between the current Microsoft Exchange environment and Office 365, which, can create significant challenges in supporting both environments and migrating, unless there is experience and expertise available.

Irrespective of the size and complexity of the organization’s messaging infrastructure, based upon Industry best practices and Microsoft guidelines the general approaches are (independent of tools used):

  • Cut Over Migration – This is more of an all-in-once migration approach aimed at smaller organizations with less than 1000 mailboxes, when the business requirement is to move all mailboxes over a long weekend, without the need for coexistence and directory synchronization. Using this approach, one can quickly provision Microsoft Exchange Online mailboxes followed by the migration of distribution groups, external contacts, email messages, calendar items, contacts and tasks to the cloud from on-premises Microsoft Exchange server.
  • Staged Migration – A majority of migrations involving medium to large organizations cannot be completed over a weekend and need a period of coexistence between on-premises Microsoft Exchange and Office 365. Since Mailboxes are migrated in batches this approach allows for coexistence where the customer can move some mailboxes to the cloud over time while maintaining the rest of mailboxes in on-premises. However the challenge using this approach is that, free/busy is not seamless and does not support all features across on-premises and Exchange Online infrastructure, like, MailTips and OOF messages.
  • Hybrid Deployment – The most complex of the three approaches, however, provides the best experience to end-users and enables seamless calendaring between hosted and on-premises users and all email looks and feels internal to the company. Recipient resolution, MailTips and OOF messages will apply to both on-premises and Microsoft Exchange Online cloud-based user mailboxes. This approach provides the ideal flexibility, particularly if there is a Business Requirement to maintain mailboxes on-premises and in the cloud for an extended period of time.

A detailed discovery of existing infrastructure and business requirements is the key for a successful migration to Microsoft Exchange Online, some high level questions that can be used to arrive at the appropriate approach:

  • Number of mailboxes in scope of migration;
  • Requirements for coexistence either with a pilot or staged migrations;
  • Key features that are absolutely need to be available between on-premises and online Microsoft Exchange organizations during the coexistence period;
  • Need for maintaining mailboxes on-premises and online – duration of coexistence;
  • Need to centralize control of mail flow from on-premises Exchange organization for both the on-premises and cloud-based organizations?

The above mentioned list of questions is not comprehensive and there are quite few key considerations:

  • Network & Security
  • Legacy Applications
  • Integration with infrastructure that would remain on-premises
  • Archived emails and PSTs
  • Active Directory  & Identity Management
  • Training and Communication 000

An unplanned migration without professional expertise that utilises industry best practices can result in data loss, downtime and impact on user productivity – negatively affecting the organization financially.

In the next blog we will talk about a typical Migration Framework