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Should I Backup Exchange Online Mailboxes?

by | Mar 5, 2019 | Cloud, Governance, Office 365

Backup? For Office 365? Are you nuts? Microsoft takes care of it, no?

Microsoft does indeed take care of the availability of the infrastructure associated to operating Office 365 and Exchange Online but the safety of your data is a shared responsibility which is clearly articulated in Microsoft’s service agreements (that you ‘sign’ when you consume Office 365 services).

Let’s face it. It is fairly unlikely that Microsoft will have a catastrophic failure within its datacenter fabric that is so serious it wipes out your Exchange Online tenant. We would go as far to say that this is extremely unlikely so what is the concern?

It is not beyond the realms of possibility that you lose access to email services for a period of time. Recent outages with Azure AD and Microsoft’s DNS capability have proven that ‘transient loss of access’ does happen, but that is about resilience – not something that backup traditionally helps with.

Why Backup?

Why would you want to backup Exchange Online mailboxes? Three reasons:

  • You decide you want to leave Office 365
  • Recovery from lost/corrupt data scenarios
  • The ‘rogue employee’

Let us look at these:

Leaving Office 365 – If you have backups of your mailboxes, service transition and egress would be simpler and undoubtedly faster. Why would you want to leave Office 365? That is something we would love to know.

Lost/Corrupt Data – Although uncommon, data corruption in mailboxes does happen – if you do not have a backup you’re in trouble because Microsoft doe not currently provide point-in-time recovery options. For lost data (the user has deleted something and time has past meaning that all the native ‘recycle bin’ options are no longer of use) you will need point-in-time restore capability to recover.

Rogue Employee – If Bob the admin gets fired and on the way out of the building he does something destructive to your Office 365 tenant you are in trouble. Without backup (that Bob and the other admins cannot get to easily!) you’re in real trouble. Relying on cached Exchange mode could be your only hope.


What is key about the decision to backup Exchange Online mailboxes or not is that you need to evaluate risk. Backup/Recovery solutions are risk mitigators, they will not prevent things from happening, they can only reduce the risk associated to the impact of an event.

Does your business need this kind of protection? Only you can decide.

Photo by Chris Yates on Unsplash