What are the options for archiving ex-employees from Office 365? We need to store an archive of their mailbox and OneDrive files.

What We Do Now

At present when a user leaves, we first disable their login. We should then migrate their mailbox to 'shared' (so it does not require a licence, and we can delete the user, and make it available to a manager). We then later need to archive this mailbox.

Problem 1: This is a very manual process and my support team have messed up on a key user, and removed his 365 licence and his mailbox got deleted after 30 days.

Problem 2: There is no easy way to archive the old mailbox to a PST file.


I was wondering if there are solutions people use for this?

I searched both SuperUser and ServerFault - oddly this does not seem to be covered in any detail, unless my search terms were faulty.


Our ideal would be an automated process that we purchase per-user that first migrates the mailbox, then after a period auto-archives to a store. I've searched solutions online and not found anything that fits.

For problem 2 we do use MigrationWiz which allows us to archive mailboxes, but again it's a multi-step manual process to make this work and too easy to mess up.

I've also seen Inactive Mailboxes (using the litigation hold feature). This uses up a licence, and I believe is being withdrawn in future.

  • I'm not sure in which country you operate, I work in European Union, and here nobody else has access to my oneDrive and mailbox, and I think it's good. If somebody leaves the company you should keep only what's really important to the company, and it should be shared with relevant people instead of just archiving. If that person had e-mails worth keeping then those mails should've cc-d to shared mailboxes in the first place instead of archiving personal mailboxes. I feel necessity of policy changes here rather than for archiving. Apr 26, 2018 at 6:37
  • Thanks for the opinion @MátéJuhász . You'll fall into all sorts of audit, contract and regulatory issues if you delete everything in this fashion. If someone has been with a company a long time, expecting them to go through years of emails and copy out important ones assumes you know what is going to be important later.
    – Quango
    Apr 26, 2018 at 9:39

2 Answers 2


Inactive Mailboxes are specifically for this use case, and the license can be re-used once the mailbox is an inactive state. You need an E3/E5 or Exchange Online Archive license applied to the "live" mailbox then have a retention rule that protects that mailbox. When the users are offboarded and the AzureAD account soft deleted, the license is removed, and the Mailbox is then considered Inactive.

The license in this scenario is automatically placed back in the pool. The inactive mailbox cannot be accessed by users. The only way to get the content is to recover the mailbox or use the eDiscovery/Content Search tools.

The above is the most common scenario I see, and the second most common is converting the mailbox to a shared mailbox. In this scenario, however, if you need ongoing protection and eDiscovery capabilities - they are supposed to be licensed.

Your other option is to configure a Hybrid setup with Exchange locally, and you can then move mailboxes back locally. You can choose to maintain them there or export them to PST files. With a local Exchange server, you also have the option of journaling messages from Exchange Online back to a mailbox locally. Obviously, these last few options can lessen any ROI of being in Exchange Online as you'll still need to maintain the infrastructure.

Go to references: Exchange licensing FAQ: https://products.office.com/en-us/exchange/microsoft-exchange-licensing-faq-email-for-business

Exchange Online Service Description: https://technet.microsoft.com/en-us/library/exchange-online-service-description.aspx

Regarding the Inactive licensing - this was something that was floated around by Microsoft last year, but they relented indicated they would remain license free for now. To my knowledge, there has not been anything recent about including a fee for inactive mailboxes.


It's pretty confusing. Microsoft's own help article suggests three methods - Remove former employee

From the article, they mention two ways to "backup" the mailbox data:

There are two ways you can save the contents of the former employee's mailbox:

Add the former employee's email address to your version of Outlook 2013 or 2016, and then export the data to a .pst file. You can import the data to another email account as needed. To learn how to do this, see Get access to and back up a former user's data.


Place a Litigation Hold or In-Place Hold on the mailbox before the deleting the user account. This is much more complicated than the first option but worth doing if: your Enterprise plan includes archiving and legal hold, litigation is a possibility, and you have a technically strong IT department.

Once you convert the mailbox to an "inactive mailbox," administrators, compliance officers, or records managers can use In-Place eDiscovery tools in Exchange Online to access and search the contents.

Inactive mailboxes can't receive email and aren't displayed in your organization's shared address book or other lists.

To learn how to place a hold on a mailbox, see the TechNet article Manage inactive mailboxes in Exchange Online.

However, my understanding is MS is moving away from ediscovery holds and is replacing them with ediscovery cases. I'm not sure exactly how they differ but it looks like you can achieve the same result with cases.

The article then mentions converting the mailbox to a shared mailbox, suggesting it's a cost effective option.

Forward a former employee's email to another employee or convert to a shared mailbox

In this step, you assign the former employee's email address to another employee, or convert the user's mailbox to a shared mailbox that you've created.

Creating a shared mailbox is the less expensive way to go because you won't have to pay for a license as long as the mailbox is smaller than 50GB. Over 50GB and you'll need to assign a license to it.

If you convert the mailbox to a shared mailbox, all the old email will be available, too. This can take up a lot of space.

If you set up email forwarding, only new emails sent to the former employee will now be sent to the current employee.

Email forwarding requires that the former employee's account has a license.

I haven't actually seen anything from Microsoft that explicitly says you can't use a shared mailbox to permanently archive a users mailbox but I think if you're dealing with a large volume of users and turnover it would be more difficult to manage the shared mailbox method.

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