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How to Create Office 365 Exchange Online Backup Set

Office 365 Backup allows you to backup your mailbox, OneDrive and Sharepoint files from your Office 365 account.


You are strongly recommended to configure or check all the settings below to confirm all the requirements are met before you proceed with the Office 365 backup and restoration:

  1. Make sure that the latest version of AhsayOBM is installed on your computer with Internet access for connection to your Office 365 account.

  2. Make sure that the Office 365 Backup feature has been enabled as an add-on module in your AhsayOBM user account and there is sufficient Office 365 Backup license quota to cover the backup of your mailboxes, OneDrive and Sharepoint files.

  3. As AhsayOBM licenses are calculated on a per device basis:

    • To backup mailboxes with 1 backup client computer / Exchange server (e.g. 1 AhsayOBM installed), 1 %edition_name% license is required.

    • To backup mailboxes with multiple backup client computers, the number of %edition_name% licenses required is equal to the number of devices. For example, if there are 10 mailboxes to be backup with 3 backup client computers, then 3 %edition_name% licenses are required.

  4. Make sure that your AhsayOBM user account has sufficient quota assigned to accommodate the storage of the Office 365 mailboxes, OneDrive and Sharepoint files for the new backup set and retention policy.

  5. The Continuous backup add-on module is required if you would like to enable the continuous backup feature.

  6. The default Java heap size setting on AhsayOBM is 2048MB. For Office 365 backup, it is highly recommended to increase the Java heap size setting to at least 4096MB to improve backup and restore performance. The actual heap size is dependent on amount of free memory available on the machine with AhsayOBM installed (machine that is running the backup).

  7. One Office 365 Backup license is required for the backup of each user mailbox. No license is required for public folder.

  8. The following subscription plans with Exchange Online email services are supported to run backup and restore on AhsayOBM: Office 365 Business Essentials, Office 365 Business Premium, Office 365 Education, Office 365 Enterprise E1, Office 365 Enterprise E3, Office 365 Enterprise E4, Office 365 Enterprise E5.

  9. Make sure your Office 365 subscription with Microsoft is active in order to enjoy all privileges that come along with our backup services. If your account has expired, renew it with Microsoft as soon as possible so that you can continue to enjoy the Office 365 backup services. When your account is expired, depending on your role, certain access restrictions will be applied to your account. Refer to the URL below for more details:

  10. User account used for the backup must be a member of the following security groups:

    • Discovery Management

    • Public Folder Management

  11. User account used to list Personal Sites, OneDrive and Outlook data of other Office 365 users must have the following roles:

    • Exchange Mail Setting: Application Impersonation and Mailbox Search

    • OneDrive Setting: Global Administrator

    • Sharepoint Setting: Global Administrator

Supported Backup Source

Below is the supported backup source for Office 365 Backup and Restore.

  1. Mailbox Level: Outlook, OneDrive and Personal Site.

  2. Folder Level: Inbox, Drafts, Sent Items, Deleted Items, Archive, Calendar, Contacts, Junk Email, Notes and Tasks.


  1. For restoration of Office 365 backup set to alternate location, there is some limitation:

    • Only administrator account or user account with administrative authority can restore backup mailbox items to an alternate location.

    • If you are trying to restore item(s) from one mailbox to an alternate location mailbox, AhsayOBM will restore the item(s) to their respective destination folder(s) with the same name of the original folder(s).

      Example: Item from “Inbox” folder of Mailbox-A will be restored to the “Inbox” folder of the alternate location Mailbox-B; Item from “Drafts” folder of Mailbox-A will be restored to the “Drafts” folder of the alternate location Mailbox-B.

    • If you are trying to restore item(s) from several mailboxes to an alternate location mailbox, AhsayOBM will restore the item(s) to their respective destination folder(s) with the same name of the original folder(s).

      Example: Item from “Inbox” folder of Mailbox-A and Mailbox-B will be restored to the “Inbox” folder of the alternate location Mailbox-C.

    • Restore of public folder item(s) to an alternate location mailbox is not supported.

      Example: Restore of public folder items from Mailbox-A to alternate location Mailbox-B is not supported.

  2. Restore of mailbox items or public folder items is only supported if the according mailbox or public folder exists.

  3. If you are trying to restore the mailbox item to a destination mailbox which has a different language setting than the original mailbox, AhsayOBM will restore mailbox item(s) to their respective destination folder based on the translation listed below. For folders such as ‘Calendar’ or ‘Notes’, a new folder ‘Calendar’ or ‘Notes’ will be created.

    Backup source (English) Action Destination mailbox with Chinese as default language settings
    Inbox Merge 收件箱
    Outbox Merge 寄件匣
    Sent Items Merge 寄件備份
    Deleted Items Merge 刪除的郵件
    Drafts Merge 草稿
    Junk E-Mail Merge 垃圾電郵
    Calendar Create new folder Calendar
    Notes Create new folder Notes

Best Practice and Recommendation

The following are some best practices or recommendations we strongly recommend you to follow before you start any Office 365 backup and restore.

  1. Temporary directory folder is used by AhsayOBM for storing backup set index files and any incremental or differential backup files generated during a backup job. To ensure optimal backup/restoration performance, it is recommended that the temporary directory folder is set to a local drive with sufficient free disk space.

  2. Consider the following best practices for optimized performance of the backup operations:

    • Enable schedule backup jobs when system activity is low to achieve the best possible performance.

    • Perform test restores periodically to ensure your backup is set up and performed properly. Performing recovery test can also help identify potential issues or gaps in your recovery plan. It’s important that you do not try to make the test easier, as the objective of a successful test is not to demonstrate that everything is flawless. There might be flaws identified in the plan throughout the test and it is important to identify those flaws.

  3. Office 365 service has set a size limit for individual mail object to be uploaded. Considering the size of the mail object may become larger as a result of the transcoding process when it is being sent out, we strongly recommend you to keep individual mail object no larger than 80MB if you definitely want it to be backed up.

  4. To provide maximum data protection and flexible restore options, it is recommended to configure:

    • At least one offsite or cloud destination

    • At least one local destination for fast recovery

  5. For backup of a large number of mailboxes, it is recommended to divide all mailboxes into multiple backup sets.

Creating an Office 365 Backup Set

Name This is the name of the backup set. You can create a meaningful name for it.
Backup set type Enter the correct backup type from the drop down box.
Username Username of the Office 365 account used for backup of mailbox, OneDrive and Sharepoint files.
Password Password of the Office 365 account used for backup of mailbox, OneDrive and Sharepoint files.
Region Region where the Office 365 account is registered.

To create a backup set:

  1. Type in a meaningful backup set name.

  2. Enter correct backup type, eg: Office 365 Backup.

  3. Enter the login details on the current page, then click Test to verify your account information. A confirmation text Test completed successfully will be shown when %edition_name% is connected to the Office 365 service account successfully.

  4. Enter correct region, eg: Global.

  5. Check the box “Access the Internet through proxy” if required.

  6. Click [Next] button to continue.