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Considerations for Protecting Office 365 with Exchange Mailboxes

Important:

On October 31, 2017, Microsoft ended support for RPC over HTTP for Office 365. For more information, see the Microsoft support article: "RPC over HTTP reaches end of support in Office 365 on October 31, 2017", https://support.microsoft.com/en-us/help/3201590/rpc-over-http-reaches-end-of-support-in-office-365-on-october-31-2017.

After December 15, 2018, Commvault will not support backup nor archiving operations using Office 365 (Exchange Online) for the Exchange Mailbox (Classic) Agent nor OnePass for Exchange Mailbox (Classic).

Transition to the Exchange Mailbox Agent. The Exchange Mailbox Agent uses EWS for backup and archiving instead of MAPI.

For information, see Transitioning to the Exchange Mailbox Agent.

Office 365 with Exchange (Exchange Online) is a hosted mail solution that is a part of Microsoft Office 365. Since Office 365 with Exchange mailboxes reside in the cloud, backing up Office 365 with Exchange mailboxes takes considerably more time than backing up mailboxes in an on-premises environment. Depending on the number of the mailboxes, a full backup job in an Office 365 with Exchange environment can span several weeks.

In addition, the Office 365 with Exchange environment has different considerations than an on-premises environment. To manage backups effectively, plan your backups accordingly, and that you make sure that you have configured your Office 365 with Exchange environment and agent properly before you run your backups.

For more information, see:

Note

Make sure that you use the correct Microsoft license. Not all Microsoft Office 365 licenses, such as Exchange Online Kiosk, support MAPI.

Plan Your Office 365 with Exchange Mailbox Backups

Planning your Office 365 with Exchange mailbox backups before you run your initial backup can help minimize the time it takes to run a backup job. We recommend that you:

  • Run a full backup for the initial backup only.

  • After the initial full backup, schedule daily incremental backups and monthly synthetic full backups.

Create User-Defined Subclients for Office 365 with Exchange Mailbox Backups

Depending on the number of mailboxes in your Office 365 with Exchange environment, it might be more effective to create multiple subclients to divide the mailboxes into groups using Mailbox affinity. This allows multiple mailboxes to be backed up at the same time. It also allows you to manage resources more effectively.

As you increase the number of mailboxes, increase the number of proxy servers in your environment to manage the subclients effectively. Assign an Online Service account to each proxy server.

Example 1

If your Office 365 with Exchange environment includes 300 mailboxes:

  • Create 5 subclients.

  • Assign 60 mailboxes to each subclient.

  • Use one proxy server.

  • Use one Online Service account.

Example 2

If your Office 365 with Exchange environment includes 3000 mailboxes:

  • Create 30 subclients.

  • Assign 100 mailboxes to each subclient.

  • Use two proxy servers (15 subclients per proxy server).

  • Use two Online Service accounts (one per proxy server).

Prevent Office 365 with Exchange Mailbox Backup Failures Caused by Permission Errors

In an Office 365 with Exchange environment, you can assign full access only to mailboxes that currently exist. As you add mailboxes, you must assign full access to the new mailboxes individually. Failure to assign access to newly added mailboxes causes backups of those mailboxes to fail. To prevent backup failures, you can assign full access to one mailbox at a time.

We recommend that you schedule a weekly or monthly task to assign full access to new mailboxes.

Prevent Office 365 with Exchange Mailbox Backup Failures Caused by Network Errors

Network errors can interrupt Office 365 with Exchange mailbox backup jobs and cause backups to fail.

Configure the agent to prevent backup failures caused by:

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