After months of planning, preparation, and migration efforts, you’ve finally moved from your on-premises Exchange 201x system to Office 365. Now you’re thinking, “do we need to keep our Exchange server(s)?” Having been personally involved in the migration to Office 365 for over 200 organizations, I’ve been asked this question more times than I can count. My standard response is, there’s no right or wrong answer; it’s a matter of preference.

Pros & Cons of Office 365

Here are the top four reasons you may want to keep (or retire) your local Exchange server(s) after an Office 365 migration:

1. Local Mailboxes are Required for Security & Compliance

Based on your company’s needs or compliance requirements, there are certain mailboxes—such as those for finance, accounting, or HR—you may want to maintain on-premises. Keeping your Exchange hybrid environment up and running allows you to have some mailboxes on-prem and others in the cloud.


2. Application and Device Relays are Needed

Most organizations have multi-function devices (MFDs) that provide a scan-to-email function for their staff. Additionally, many third-party applications require the ability to send emails from within the program. While newer MFDs and applications offer direct interoperability with Office 365, older systems may not support the authentication and/or protocol requirements for sending direct to Office 365. In these cases, maintaining the Exchange server provides for an on-premises relay to accommodate these legacy systems’ send requirements.


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3. Public Folder Migration Takes Resources

If you have a lot of public folders, or even a few very large ones, in your Exchange Organization, there could be a sizeable investment of time, effort, and resources to move them to Office 365. Keeping the Public Folders on-premises provides additional planning and migration time, and allows you the option of not migrating and just maintaining them  while you look to move the data to SharePoint Online.


4. Management of Attributes (and this is the big one)

The biggest reason a company may opt to keep an Exchange hybrid server on-premises is management. Once a mailbox migration has been completed and the Exchange servers removed, administrators lose the ability to modify mail-related attributes for a user in a graphical interface (GUI) instead of relying on Azure PowerShell or ADSIedit/Active Directory User Attribute editing. While this may not sound like a big deal, imagine every time you want to add or modify a user’s email address or aliases (such as in the case of marriage or divorce), or if you need to update membership of a group, you have to go into the object’s AD account properties and make changes manually by hand-typing them.

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By keeping that Exchange hybrid server around, you can continue to create, modify, or delete mail-related properties for users and groups just as you always have—from the Exchange Admin Center.

As I’ve said, there’s no right or wrong answer regarding keeping or decommissioning the Exchange server once you’ve completed the migration to Office 365; it’s just a matter of choice. We recommend your Exchange team weigh all the pros and cons before deciding to pull the plug on your Hybrid server.

Contact us if you’d like to discuss how we might help your team and support your cloud initiatives.

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