What are the possible options for recovering Exchange Online mailbox? | Part 4#23 5/5 (1) 11 min read

In the current article, we will review in high level the different options, for recovering Exchange Online mailbox.Before we dive into the deep water off – “Exchange Online restores mailbox scenario” and specific details of the restore process that will be reviewed in the next articles in the current article series.
It’s important that we will understand a couple of concepts that relate to the process of restoring Exchange Online mailbox.Using the information about the different Exchange Online mailbox recovery options, that we review, will help us to choose the “best recovery method” for our particular need.

Restore Exchange mailbox | Article Series table of content | Click to expand

Restore Exchange Online deleted mailbox | Article Series

Exchange Online mailbox restore | Articles series table of content
Introduction to the subject of Exchange and deleted mailboxes
01Restore deleted Exchange Online mailbox in Office 365 environment | Prefix | Part 01#23
02Directory Object Deletion and the restore “domino effect + little bit about the concept of the Active Directory Recycle bin | Part 2#23
03What are the possible causes for an Exchange Online mailbox deletion? | Part 3#23
04What are the possible options for recovering Exchange Online mailbox? | Part 4#23
05The Index of the different Exchange Online mailbox restores methods| Part 5#23
Restoring Exchange Online mailbox – cloud only environment
06Restore Exchange Online Room mailbox | Cloud only (Fully Hosted) environment | Part 6#23
07Restore Exchange Online Shared mailbox | Cloud only (Fully Hosted) environment | Part 7#23
08Restore Exchange Online user mailbox | Cloud only (Fully Hosted) environment | Article 1#3 | Part 8#23
09Restore Exchange Online user mailbox | Cloud only (Fully Hosted) environment | Article 2#3 | Part 9#23
10Restore Exchange Online user mailbox | Cloud only (Fully Hosted) environment | Article 3#3 | Part 10#23
Restoring Exchange Online mailbox in Directory synchronization environment
11The special characters of Directory synchronization in an Office 365 environment | Article 1#2 | Part 11#23
12The special characters of Directory synchronization in an Office 365 environment | Article 2#2 | Part 12#23
Restoring user account – On-Premise Active Directory environment
13Deleted Active Directory User account and the Deleted object store | Basic introduction | Article 1#4 | Part 13#23
14How to restore Active Directory deleted user account (Active Directory recycle bin is not enabled) using LDP.EXE | Article 2#4 | Part 14#23
15How to restore Active Directory deleted user account (Active Directory recycle bin is not enabled) using AdRestore, AdRestore.net and LEX – the LDAP explorer | Article 3#4 | Part 15#23
16How to restore Active Directory deleted user account by using Active Directory recycle bin | Article 4#4 | Part 16#23
Restoring Exchange Online mailbox in Directory synchronization environment
17Restore Exchange Online USER mailbox | Directory synchronization environment | The “right way” | Part 17#23
18Prefix – the “Problematic” Exchange Online mailbox restores scenarios in Directory synchronization environment | Part 18#23
19Reviewing the characters of Exchange Online mailbox recovery mistake – New On-Premise Active Directory User Account was created | Part 19#23
20Reviewing the characters of Exchange Online mailbox recovery mistake – Soft Deleted Office 365 was restored | Part 20#23
21Solving an Exchange Online mailbox restore mistake by Restoring the original Soft Deleted Active Directory user | Part 21#23
22Restoring Exchange Online mailbox content to another mailbox using PowerShell command New-MailboxRestoreRequest | Part 22#23
23Solving an Exchange Online mailbox restore mistake Office 365 user was restored – removing the ImmutableID value | Part 23#23

Recover user account versus recover Exchange Online mailbox

Let’s start with a “strange” declaration – most of the times, the recommended method for recovering Exchange Online mailbox is – recover the user account that considers as the mailbox owner.

Theoretically, there could be a scenario in which the Exchange Online mailbox considered as “deleted “and the user account that associated with the mailbox, consider as “alive” (active user account). But 99% of the time we will face a scenario in which the Exchange Online mailbox + the user account that associated with the Exchange Online mailbox are both consider as “deleted.”

In Office 365 based environment the simplest and recommended method is to recover the deleted user who associated with the deleted Exchange Online mailbox.

The user account “restore process” will start an automatic process which will lead to the restoration of the Exchange Online mailbox.

Restoring the mailbox owner will start automatic process of restoring the deleted Exchange Online mailbox

The opposite is not true.

Theoretically, the restore process of Exchange Online mailbox was supposed to “lead” to the restoration process of the deleted user account that considers as the mailbox owner.
From my experience, at the current time, this process is not working properly, and most of the time (if not all the time), the result could be a corruption of the Exchange Online mailbox that was supposed to restored.

Let’s start again, from the begging and describe the two types of “objects” that can restore.

When we approach the task of – restoring Exchange Online mailbox, we can start the process of restoring the user account that associated with the mailbox, or the another option is – to start the restore process from the other side meaning – accessing the deleted Exchange Online mailbox.

The possible objects that we can recovered - User account versus Mailbox -01

Regarding the option of – restoring directly the Exchange Online mailbox, there are a couple of scenarios that we can choose from:

The possible objects that we can recovered - mailbox -03

A. Restoring a Soft Deleted User account

When we restore a user account, we can define two major scenarios:

A.1 Cloud only (fully hosted)

The term “cloud only” describe Office 365 infrastructure in which the user account and the Exchange Online mailboxes are fully hosted and managed by using the Office 365 infrastructure.

In this type of environment, we will restore the Office 365 user account that is “stored” in the Azure Active Directory by using the Office 365 admin center.

A.2. Directory synchronization environment

The term “Directory synchronization environment” defines an infrastructure in which the organization uses two sets of “directories” the On-Premise Active Directory + the Office 365 Directory (Azure Active Directory).

In this type of environment, we will restore on the On-Premise Active Directory user, and not the Office 365 user account.

The reason is that in a Directory synchronization environment, the On-Premise Active Directory defines as the “source of authority” meaning the “owner” of the synchronized user account. The Office 365 Directory (Azure Active Directory) considers as a “replica” of the On-Premise Active Directory user account.

In this case, will need to restore the “original user account” (the On-Premise Active Directory user account) which will activate an automatic process that will lead to the restoration of the Office 365 user account and at the end, the restoration of the deleted Exchange Online mailbox.

The possible objects that we can recovered - User account -02

In the Office 365 environment, when we restore a user account that was the owner of Exchange Online mailbox,

The Azure Active Directory “send” the information about the “restored user account” to the Exchange Online infrastructure.

Exchange Online “understand” that he needs to “fetch” the deleted Exchange Online mailbox from the recycle bin, and “attach” the restored mailbox to the restored user account.

In most of the scenarios, this is the preferred or recommended recover mailbox scenario.

Most of the time, we prefer to rematch the user who was the Exchange mailbox owner with “his mailbox.”

Restoring the Exchange mailbox owner User account -01

B. Restore the Exchange Online mailbox

The other type of approach for implementing the process of restoring Exchange Online deleted mailbox is – start the restore process, by addressing “directly” to the Exchange Online mailbox.

B.1 Restore the Exchange Online mailbox

The operation of “restoring Exchange Online deleted mailbox” can be implemented in one of the following ways:

B.1.1 – Restore the Exchange Online mailbox to the Original Owner

As mentioned, theoretically, this option could seem like a reasonable option because, in many scenarios, we would like to restore the Soft Deleted Exchange Online mailbox + the Soft Deleted User account that associated with the mailbox.

The “catch” is that in Office 365 the operation in which Exchange Online infrastructure needs to address the Azure Active Directory and “inform” that the Soft Deleted user account should restore, is not working for some reason, most of the times.

In the next section, I would demonstrate such a scenario.

Restoring the Exchange mailbox - Scenario 3#3 -04

B.1.2 – Restore the Exchange Online mailbox to the “Another user account.”

The scenario that will

In the above problematic scenario, we can ask to restore a deleted Exchange Online mailbox, but also, ask to create a NEW Office 365 user account and bind the restored Exchange Online mailbox to this NEW account.

Restoring the Exchange mailbox - Scenario 1#3 -02

B.2 – Restore the Exchange Online mailbox content

The additional interesting option that we can use is – restoring the content of Soft Deleted Exchange Online mailbox instead of the mailbox itself.

In this type of scenario, the Soft Deleted Exchange Online mailbox will continue to stay in the Exchange Online recycle bin (keep considering as Soft Deleted mailbox).

The restore process will be implemented by accessing the Soft Deleted Exchange Online mailbox and copy all or part of the information that is store din the Soft Deleted mailbox to “another” Exchange mailbox.

For example – a scenario of leaving employee whom his Active Directory user account and his Exchange Online mailbox where deleted.

The “deleted Exchange Online mailbox” will stay at the Exchange Online recycle bin for 30 days.

We got a request to recover a particular E-mail item from the “deleted Exchange Online mailbox” of the specific employee.

Notice that we don’t want to recover the “hole deleted mailbox,” but instead, just a particular E-mail item.

The option of recovering a specific content from a soft deleted Exchange Online mailbox is implemented by using the PowerShell command: New-MailboxRestoreRequest

Restoring the Exchange mailbox - Scenario 2#3 -03

The problematic and not recommended scenario of – restoring Exchange Online mailbox and recover the original mailbox owner user account

As mentioned, in the former section I have expressed my reservations from this option.

The interesting thing is that Exchange Online includes a graphical interface that “offer” us the option of recovering a Soft Deleted Exchange Online mailbox by using a simple one-click operation.

Theoretically, the option of using a simple graphic interface may seem very appealing, but in reality, the process of recovering a Soft Deleted Exchange Online mailbox via the Exchange Online admin interface will most of the time lead to unpredicted results.

I’m sure that at some point in time the “restored mailbox button” will be removed from the Exchange Online admin center interface or the another option is that the problem that caused by this “restore mailbox button” will be fixed.

At the current time, there is no formal information on this option and the logic that implemented by the “restored mailbox button.”

From my experience, each time that I try to test the possibility of recovering Exchange Online Soft Deleted mailbox using the “restored mailbox button,” the consequence was a destruction of the Soft Deleted mailbox.

The normal human responds to the former information will be – “Ok, now I’m curious, show me this dangerous option!”

To be able to experience the problematic scenario of restoring Exchange Online mailbox via the Exchange Online admin interface let’s use the following scenario:

A user named – Adele deleted and the Exchange Online mailbox that associated with the Adele user account.

We were asked to restore Adele Exchange Online mailbox and the Adele user account, so Adele will be able to login to her Exchange Online mailbox.

To fulfill this requirement, all we need to do is:

  • Log in to the Exchange admin center
  • On the left menu bar – select the recipients menu
  • On the top menu bar – select the mailboxes menu
  • Click on the three dots icon
  • Select the menu – Deleted mailboxes.

Restoring the Exchange Online mailbox and restored the original Soft Deleted Office 365 user account -01

In our example, we can that the Exchange Online recycle bin, include Adele Soft Deleted mailbox. As mentioned, we would like to recover Adele’s mailbox.

  • We select Adele’s name and click on the “recover” menu option
  • In the next recovery wizard window, we click on the recover button

Restoring the Exchange Online mailbox and restored the original Soft Deleted Office 365 user account -03

The following notification appears

After you create a new mailbox, you must go to the Office 365 Admin Center and assign the mailbox a license, or it disabled after the grace period.

The Exchange Online recycle bin restore wizard “inform” us that after the phase in which the original Office 365 user account will also restored, we will need to access the “restored Office 365 user account” and assign him the required Office 365 license.

Restoring the Exchange Online mailbox and restored the original Soft Deleted Office 365 user account -04

When looking at the Exchange Online recycle bin, we can see that Adel mailbox was restored (doesn’t appear anymore in the Exchange Online recycle bin).

Restoring the Exchange Online mailbox and restored the original Soft Deleted Office 365 user account -05

When we access the properties of the “restored Adele mailbox.”

The operation couldn’t be performed because object ‘eccbee51-0244-44ca-853a-91f9a370693f’ couldn’t be found on ‘DB3PR05A001DC02.EURPR05A001.prod.outlook.com’.

Restoring the Exchange Online mailbox and restored the original Soft Deleted Office 365 user account -06

Restore Exchange Online mailbox | Article series index

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What are the possible options for recovering Exchange Online mailbox? | Part 4#23
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What are the possible options for recovering Exchange Online mailbox? | Part 4#23
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In the current article, we will review in high level the different options, for recovering Exchange Online mailbox.Before we dive into the deep water off - “Exchange Online restores mailbox scenario” and specific details of the restore process that will be reviewed in the next articles in the current article series, it's important that we will understand a couple of concepts that relate to the process of restoring Exchange Online mailbox.Using the information about the different Exchange Online mailbox recovery options, that we review, will help us to choose the “best recovery method” for our particular need.
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