This content is part of the Essential Guide: The essential Office 365 migration guide

Comparing Office 365 pros and cons with Exchange 2013, hybrid setups

Before upgrading your email setup, weigh Office 365 pros and cons with those of potential Exchange 2013 or hybrid deployments.

Welcome to the final installment of our three-part series on email migration decisions. In part one, we looked...

at new features in Exchange 2013 that could sway migrations plans. In part two, we examined feature and cost considerations for both Exchange 2013 and Office 365. Now, we'll examine the various pros and cons that companies should expect from Exchange 2013, Office 365 and hybrid deployments.

When weighing a potential email migration, remember that factors will vary in importance from organization to organization. Therefore, it's important to assign a relevant weight to each pro and each con in terms of what's most important to you.

Considering that Office 365 will continue to develop and expand its feature set, it's worth reviewing the Office 365 wikis to see if features that initially might make it less attractive are due for an update in a reasonable time frame.

Exchange 2013 on-premises pros and cons

Table 1 details the pros and cons of maintaining an on-premises Exchange 2013 environment, should you decide to focus upgrade plans there.

Table 1. The pros and cons of an on-premises Exchange 2013 deployment.

Exchange 2013 on-premises pros and cons
Pros Cons
You maintain complete control of your environment, including the hardware, software, backups and recovery. You also control the allocation of mailbox and transport limits (e.g., you control the mailbox sizes for each user, and the size of the messages that can be sent and received), as well as any third-party products that you'd like to integrate with your mail environment.

Can be more costly than cloud-based alternatives because you own and maintain all the hardware and software. Additionally you must maintain a high level of in-house skill, especially if you've deployed a high-availability environment that is spread across a number of data centers. Running a high-availability-based infrastructure requires a deep understanding of networking, Windows clustering, Exchange database log replay, and resilient client access and transport servers.

Your email data is completely within your sight, so you know where it is, as well as who is accessing it. You control all security within your environment. Running multiple Exchange servers in-house contributes to your organization's overall carbon footprint. Therefore, you need to power and cool each of the servers, as well as the associated networking equipment.
You have the freedom to schedule in your own maintenance windows for upgrades. Therefore, uptime is completely within your sphere of influence. You need to maintain the environment and perform all necessary planning required to move between cumulative updates.
You get all of Exchange 2013's associated features and functionalities.
Speed of access is often more favorable with on-site scenarios, as the infrastructure is close to the user base.

Office 365 pros and cons

Table 2 gives an overview of the pros and cons of a cloud-based email environment, should you wish to move your email to Office 365.

Table 2. The pros and cons of an Office 365 environment.

Office 365 pros and cons
Pros Cons
You reduce your overall capital and revenue costs on hardware and software.

You are technically no longer in control of your data, nor of how it is handled when it's out of your sight.

You can reduce your ongoing staffing and administration costs.

If your organization has strict data protection rules, certain email messages are already routed and stored in a specific way. If you migrate to Office 365, you may not be able to guarantee that these requirements are met, as your data could reside in any number of data centers across the world.

Uptime is guaranteed to be 99.9 % and is financially backed.

When you need to integrate other business systems into your environment, you may be limited in what you can achieve, compared with hosting it yourself. For example, it might be impossible to integrate a customer relationship management application with your mail system via an API or physically installed software component.
You can connect from almost anywhere. You are not in control of subscription costs as your business grows.

Hygiene and other third-party services are integrated into the overall subscription cost of the deployment.

It may be unclear how you can integrate your data back into your organization if you terminate the contract.

Hybrid deployment pros and cons

Table 3 gives you an overview of the pros and cons of maintaining a hybrid deployment, which is a combination of an on-premises Exchange 2013 (or a previous version of Exchange that supports the hybrid model) and Office 365.

Table 3. The pros and cons of a hybrid deployment.

Hybrid deployment pros and cons
Pros Cons
Provides the best of both worlds, allowing you to maintain some degree of control over security, integration and data. Can prove complex to set up and manage, and doesn't allow you to immediately leverage full savings in terms of staff, software and hardware costs.

Allows for staged migrations for large environments at a controllable pace, letting you scale up to a utility model, where your monthly or yearly expenditure is proportionate to the number of mailboxes that you have.

Is more expensive since you are paying for both your in-house and off-site infrastructure.

Allows you to evaluate hosted Exchange services without committing your entire user base.

Gives you a "mixed economy" and inconsistent user feature set. Some users will have the benefits of being in-house, whereas others will have a reduced experience in the cloud.

Final thoughts

Making a decision among the three above-described options is no doubt a complex undertaking, and is one that must be linked directly to your organization's business needs. Remember, the least expensive solution might not also be the most effective in the long term.

People often ask me "Will we all be in the cloud in five years?" My answer is "Probably not."

Each organization has unique security standards and cultural requirements, and the cloud model for email and collaborative applications does not fit them all.

It may be more realistic to expect that over the next five years or so, IT shops will embrace the hybrid approach, where some services are on-premises and some are in the cloud. This mixed approach allows administrators to keep aspects of the application in-house for security or management reasons, but also offload some tasks to providers, freeing time for more strategic decisions and tasks.

About the author:
Andy Grogan is a multiple recipient of the Microsoft Exchange MVP award (2009-2013). He is based in the U.K. and has worked in the IT industry for the last 16 years, primarily with Microsoft, HP and IBM technologies. His main passion is Exchange Server, but he also specializes in Active Directory, SQL Server, storage solutions, technology strategy and technical leadership in large-scale enterprises. He currently works for a large county council in Surrey as its technical delivery manager and supports 15,000 customers on more than 240 sites. Visit Andy's website,

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