When mailboxes grow too large you won’t be able to receive or send mail anymore. Another common issue with large mailboxes is that Outlook will take longer to load. To solve this we can use Online Archives in Outlook.
Online Archive mailboxes are available for Office365 users with the correct license. The advantage of online archives (also known as In-Place archives), is that older emails are automatically archived in a separate archive mailbox.
What is Outlook Online Archive
Before we are going to take a look at the requirements and how to use the Online Archive, let’s first take a look at what Outlook Online Archive is exactly. And how it’s different from the normal archive.
Note
The Outlook Online Archive is named differently throughout the documentation. It’s also refered as In-Place Archive or Exchange Online Archive.
As the name implies, it’s an online archive mailbox. This gives the Exchange Online Archive a couple of important characteristics:
- It’s only accessible with an internet connection
- Data isn’t stored on the user’s computer – saving disk space
- It’s a separate mailbox
By archiving email to the In-place archive you can thus free up disk space on the user’s computer. This will also help with reducing the loading time of Outlook. And it also helps with cleaning up the mailbox, because by default Outlook only searches in the primary mailbox.
Online Archive vs Archive folder
Every Outlook mailbox comes with an Archive folder. Users can move emails to their archive folder to clean up their inbox or use the Archive button for this. The difference between this folder and the Online Archive is that the Archive folder is part of the primary mailbox of the user.
This means that it doesn’t reduce the mailbox size and that email items in the archive are still displayed in the search result.
| local PST File | Archive Folder | Online Archive | |
|---|---|---|---|
| Location | Local Computer | Primary Mailbox | Exchange Online |
| Max Size | 50GB | Part of mailbox | 50GB/1.5 TB |
| Displayed in the search result | No | Yes | No |
| Accessible from | Local computer | Anywhere | Internet required |
You can also archive your mail to local PST files. The problem with PST files is that you will need to be sure that they are backed up. Otherwise, you risk losing data when the user’s device is lost or the hard drive crashes.
Another problem with PST files is that they can only be accessed from the computer where the PST file is located. The online archive, for example, can also be accessed from Outlook Online or the Outlook App.
Exchange Online Archiving License
The Exchange Online Archive is available with most Office 365 plans. Depending on your license you will have access to either 50GB or 1.5TB of archiving space.
The following plans have access to 50GB of archive space:
- Microsoft 365 Business Basic
- Microsoft 365 Business Standard
- Office 365 E1
And the plans below have an Online Archive of 1.5TB:
- Microsoft 365 Business Premium
- Office 365 E3
- Office 365 E5
- Microsoft 365 E3
- Microsoft 365 E5
Shared and Resource mailboxes also have an Exchange Online Archive mailbox, but these are limited to 50GB. If you need a larger archive for a shared mailbox you will need to assign an E3 or E5 license to the mailbox.
Online Archive Size Limit
Good to know is that the 1.5TB archive limit isn’t the initial archive size. The online archive is initially limited to 100Gb. When the only archive is almost full (at 90%) you can increase it with auto-expanding archiving.
This will add another 100Gb of storage limit until the archive reaches the limit of 1.5Tb. Keep in mind that it can take up to 30 days before the additional storage space is added.
Note
Online Archive mailboxes can’t be used anymore for journaling or bulk archiving methods (like the use of transport rules). Microsoft has applied a growth limit of 1 GB per day for archiving mailboxes. The archive mailbox can only be used by the individual user or shared-mailbox it belongs to.
Enable Archive Mailbox in Office 365
The Exchange Online Archive is enabled by default for your users. When you want to use the online archive you will have to enable it either per-user or for your entire organization. To enable it we can either use the Microsoft Purview Compliance portal (formerly known as Microsoft 365 Compliance) or PowerShell.
- Open Microsoft Purview (Microsoft Compliance Center)
- Click on Data lifecycle management
- Select the user
- Click Enable Archive
Using the Exchange Admin Center
We can also enable the Online Archive Mailbox through the Exchange Admin center. But also here you will need to enable it per user:
- Open the Exchange Admin Center
- Expand Recipients and select Mailboxes
- Click on the user
- Click on Others
- Open Manage mailbox Archive
- Enable the Mailbox Archive
Using PowerShell to enable Online Archive
These methods are great if you only need to enable the archive mailbox for a couple of Office 365 users. When you want to enable the archive mailbox for all or multiple users in your organization you can better use PowerShell.
Note
Make sure that you have installed the Exchange Online Module before you continue.
The online archive mailbox needs to be enabled per mailbox. The advantage of PowerShell is that we can easily select all users or a group of users. First, open PowerShell and connect to Exchange Online:
# Connect to Exchange Online
Connect-ExchangeOnline -UserPrincipalName [email protected]
To enable the archive mailbox for a single user we can use the following PowerShell command:
Enable-Mailbox -Identity [email protected] -Archive
After you have enabled the Online Archive it will become visible in Outlook below the primary mailbox. Sometimes the user needs to restart Outlook before they are able to access the online archive.
To enable the archive mailbox for all users we can first get all mailboxes that don’t have an archive GUID set, which indicates that an archive mailbox isn’t active. And filter the selection on only user mailboxes.
# You can first verify the list of mailboxes with:
Get-Mailbox -Filter {ArchiveStatus -Eq “None” -AND RecipientTypeDetails -eq “UserMailbox”} | ft
# Enable archive mailbox for all users:
Get-Mailbox -Filter {ArchiveStatus -Eq “None” -AND RecipientTypeDetails -eq “UserMailbox”} | Enable-Mailbox -Archive
Enable Auto-Expanding Archive
If your license includes Exchange Online Archive up to 1.5TB, then I suggest that you also enable Auto-Expanding Archive. Just like the archive mailbox, we will need to enable it for every existing user. But first, we need to enable the feature of the organization.
Make sure that you are connected to Exchange Online in PowerShell and run the following command to enable auto-expanding archive for your tenant:
# Connect to Exchange Online
Connect-ExchangeOnline -UserPrincipalName [email protected]
# Enable auto-expanding archive
Set-OrganizationConfig -AutoExpandingArchive
You can verify the setting with the following command:
Get-OrganizationConfig | select AutoExpandingArchiveEnabled
When auto-expanding is enabled for your organization it will automatically enable it for new mailboxes. But for existing mailboxes we will need to enable auto-expanding manually with PowerShell:
# Enable it for a single mailbox
Enable-Mailbox [email protected] -AutoExpandingArchive
# Or for all users:
Get-Mailbox | where {$_.AutoExpandingArchiveEnabled -eq $false} | Enable-Mailbox -AutoExpandingArchive
Using the Exchange Online Archive
Archiving of mailbox items is done based on policies. The default policy, which is applied to all mailbox folders, is to move the item (email) after 2 years to the online archive.
Good to know is that the folder structure of your inbox is automatically re-created in the Online Archive. So if you have for example a subfolder Invoices in your Inbox, then you will get the same subfolder in the Online Archive:
Manually move items to Online Archive
It’s also possible to manually move items to the Online Archive. This is useful when you want to clean up your mailbox or are running out of storage space.
- Select the items that you want to move to the Online Archive
- Right-click on the selected items
- Choose Move and select the Inbox – Online Archive folder
Don’t use the Archive button in the toolbar, because that will move the selected items to the archive folder in the primary inbox.
Exchange Online Archiving Policies
Exchange Online Archiving is based on policies. The default policy that is applied to all mailbox folders is “move to archive after 2 years”. This means that emails will automatically be moved to the Outlook Online Archive 2 years after you received or send them.
There are 4 possible archiving policies that you can currently apply to your mailbox folders:
- Use Parent Folder Policy (2 years)
- 1 Year
- 5 Year
- Never
It’s possible to change the policy on your inbox or on a subfolder. You could for example archive all inbox items after the default 2 years, but the invoice after 1 year.
- Right-click on the folder and select Properties
- Open the Policy tab
- Change the Online Archive Policy to 1 year
Add or Change Exchange Archiving Policies
In the old Exchange Admin Center, you could easily add or change Retention Tags that are used for the online archiving policies. Only with the latest change to the Microsoft Purview Center, this option isn’t available anymore.
So to change the default policy or add a new policy you will need to use PowerShell. To view the existing retention policies we can use the following cmdlet:
# First connect to exchange online
Connect-ExchangeOnline -UserPrincipalName [email protected]
# Get all archiving policies
Get-RetentionPolicyTag | where {$_.RetentionAction -eq ‘MoveToArchive’}
# Result
Name Type Description
—- —- ———–
Recoverable Items 14 days move to archive RecoverableItems Managed Content Settings
Default 2 year move to archive All Managed Content Settings
Personal 1 year move to archive Personal Managed Content Settings
Personal never move to archive Personal Managed Content Settings
Personal 5 year move to archive Personal Managed Content Settings
When the default policies are not sufficient, then it’s possible to add a new policy using PowerShell. There are a couple of parameters important:
- RetentionEnabled – Enable or disables a policy rule in Outlook
- AgeLimitForRetention – Apply policy after x days
- RetentionAction – set to MoveToArchive for Online archiving
- Type – Personal or use All when you are creating a new default policy
To archive the email items after 6 months we can create the following policy for example:
New-RetentionPolicyTag “Personal 6 months move to archive” -Type Personal -RetentionEnabled $true -AgeLimitForRetention 180 -RetentionAction MoveToArchive
We can also set or change the default policy. Let’s say you want to move all items to the archive after 1 year by default.
# Create a new default policy
New-RetentionPolicyTag “Company Default 1 year move to archive” -Type All -RetentionEnabled $true -AgeLimitForRetention 365 -RetentionAction MoveToArchive
Using the New Policy
The new policy won’t be listed in Outlook by default. The user will first have to add the new policy to their mailbox account.
- Right-Click on a mailbox and choose Properties
- Open the Policy tab
- Click on Add or Remove Retention Policies
Outlook Online will open in the Settings screen.
- Click on Add new policy
- Select the newly created policy and click save
You can now use the newly created policy in Outlook and Outlook Online. Go back to the folder properties in Outlook (close the properties and re-open them). The policy to move the items after 6 months is now available under Online Archive
Searching in Online Archive
When you search for an item in Outlook it will by default search in the current mailbox. To search in the online Archive as well you will need to select All Mailboxes next to the search field.
When you only want to search through the online archive, you will first need to select the Online Archive in the folder list, and then start the search.
Wrapping Up
Using the outlook online archive is a great way to reduce the mailbox space and keep your inbox clean. Make sure that you inform your users about the policies and when emails are moved to the archive folder.
The default Exchange Online Archiving policies are for most situations more than fine, they give a nice balance in quickly finding emails when users are searching and keeping the primary mailbox at a decent size.
ref: Outlook Online Archive for Office 365 Explained — LazyAdmin