Pros and Cons of Exchange Online vs On-Premises

I get this question a lot and it’s often asked by people who are still on the edge of deciding if they want to migrate their users. Let’s run a break down of the pros and cons of Exchange Online vs On-Premises. The Pros of one in this case is the con of the other.

Pros of Exchange Online

  • Mailbox Uptime
    • Microsoft has excellent SLAs in place to ensure your mailbox is online and accessible
    • Maintenance for exchange on-prem won’t effect Exchange Online mailboxes
  • Mailbox Flexibility
    • With Exchange Online, you won’t have to connect to your company’s VPN to access your mailbox
    • You can access it from anywhere as long as you have an internet connection
  • Mailbox Security
    • Exchange Online allows for simple and integrated implementation for Multi-Factor Authentication with Azure Active Directory
    • Audit logs are also easily integrated and searchable
  • Infrastructure and Storage
    • One of the biggest benefits is not having to maintain a full blown Exchange environment
    • Exchange Hybrid shops will still require an onprem exchange server but 1 server should be sufficient for your needs
    • Exchange Online mailboxes can have 100GB + Unlimited Archiving
    • Retention Policies and Litigation hold can keep a mailbox for as long as you need
    • Your data has redundancy across the many Microsoft Datacenters


    Pros of Exchange On-Premises

  • Speed
    • With Servers being hosted in your own Datacenter, often times it might be faster than the cloud
  • Cost
    • While Exchange Online does offer very competitive pricing, sometimes cost can be a factor



I’ve managed onprem Exchange and Exchange Online and I think a hybrid Exchange with your mailboxes migrated to the cloud is really the sweet spot. You get the benefits of the infrastructure, redundancy, security, vertical integration with other platforms and the flexibility to connect from anywhere. I love the fact that you can secure your account with Microsoft Authenticator and MFA and you don’t have to connect to your company’s VPN to access your mailbox. It’s also helpful for other services such as Microsoft Teams.

Although I would definitely prefer having my mailboxes hosted in Exchange Online, the decision is really dependent on each and every shop. Some shops might have very strict requirements and have to abide to certain laws. Hopefully this quick and dirty list of the pros and cons of Exchange Online vs On-Premises was helpful for you and made your decision to move to the cloud or stay onprem a bit easier.

If you are thinking of migrating your users to the cloud, using the Hybrid Exchange model, I’ve already got you covered. The process has gotten so much better (and easier) these days compared to the steps in the past. I even went ahead and made a step by step guide to installing Azure AD Connect and migrating users to the cloud.

Thank you for taking the time to view the benefits of exchange online and seeing what exchange On-Premises has to offer. If you want to see more cloud content, take a look at our Office 365 and Azure Active Directory categories. I’m sure there’s something there that will catch your eye.

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Paul Contreras

Hi, my name is Paul and I am a Sysadmin who enjoys working on various technologies from Microsoft, VMWare, Cisco and many others. Join me as I document my trials and tribulations of the daily grind of System Administration.

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