{"id":122120,"date":"2023-01-30T08:41:25","date_gmt":"2023-01-30T08:41:25","guid":{"rendered":"https:\/\/www.stellarinfo.com\/blog\/?p=122120"},"modified":"2025-09-01T07:25:44","modified_gmt":"2025-09-01T07:25:44","slug":"how-to-migrate-large-archive-mailbox-to-microsoft-365","status":"publish","type":"post","link":"https:\/\/www.stellarinfo.com\/blog\/how-to-migrate-large-archive-mailbox-to-microsoft-365\/","title":{"rendered":"How to Migrate Large Archive Mailbox to Microsoft 365?"},"content":{"rendered":"

In local Exchange Server, user archives are stored on the local server instead of local PST file. This is same in Exchange Online. The only difference is that there is no archive mailbox size limit on local server, whereas there is size restriction for archive on the Exchange Online.<\/p>

For Microsoft 365 Business Basic and Business Standard<\/strong> plans, there is a 50 GB archive limit. For the Business Premium, the maximum size limit is 1.5 TB for archive. Here’s the full list of size limits as per Microsoft 365 subscriptions:<\/p>

Subscription<\/strong><\/td>Archive Limit<\/strong><\/td><\/tr>
Business Basic<\/td>50 GB<\/td><\/tr>
Business Standard<\/td>50 GB<\/td><\/tr>
Business Premium<\/td>1.5 TB<\/td><\/tr>
Enterprise E3<\/td>1.5 TB<\/td><\/tr>
Enterprise E5<\/td>1.5 TB<\/td><\/tr>
Enterprise E1<\/td>50 GB<\/td><\/tr>
Enterprise F3<\/td>N\/A<\/td><\/tr><\/tbody><\/table><\/figure>

For standalone plans, the following archive size limits will apply.<\/p>

Plan<\/td>Archive Limit<\/td><\/tr>
Exchange Online Plan 1<\/td>50 GB<\/td><\/tr>
Exchange Online Plan 2<\/td>1.5 TB<\/td><\/tr>
Exchange Online Kiosk<\/td>N\/A<\/td><\/tr><\/tbody><\/table><\/figure>

So, during migration, you may face issues if your local archive is larger than the limit provided in the online tenant’s plan or subscription you have bought and provisioned for the user. Therefore, it is recommended to prepare the migration checklist beforehand to avoid any issues.<\/p>

How to Migrate Large Archive Mailboxes to Microsoft 365?<\/h2>

You need to do some planning prior to the migration of archive mailboxes. This includes identification of the total size and item counts of each archive you want to migrate. Now depending on the size of archive, you need to apply the right license in Microsoft 365 – be it 50 GB or 1.5 TB archive plan. Although you can opt for the Premium or Enterprise subscription, you still need to do auto expansion of the archive on the online tenant as the 1.5 TB limit is not automatically allocated.<\/p>

Auto expansion works as given below.<\/p>

\"User<\/figure>

Enable Auto Expanding on Online Archives<\/h3>

To enable auto expanding on archives in Microsoft 365, you need to first connect to the tenant using the Exchange Online PowerShell. This is the command for the entire organization.<\/p>

Set-OrganizationConfig -AutoExpandingArchive<\/code><\/p>

\"Set-OrganizationConfig\"<\/figure>

After setting up the auto expanding archive for each and every mailbox, you need to perform the data clean-up process to remove unneeded data and large attachments, and save them in a SharePoint Online site or Microsoft Teams Site. You can also remove the data with a business retention procedure. When you reduce the amount of data to be uploaded, this ensures integrity of the mailboxes. It is suggested to retain the data on a file server as PST files are not secure and can be copied or opened in another Outlook application outside the organization.<\/p>

Though the auto expanding feature is enabled, it doesn’t mean that it is expanded to the limit immediately. It will be expanded automatically bit-by-bit when the mailbox reaches a certain threshold.<\/p>

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Read More : <\/strong>How to Migrate Mailboxes over 100GB to O365?<\/a><\/p>\n<\/blockquote>

Migrate Archive Mailboxes using Exchange Admin Center (EAC)<\/h3>

To migrate the mailboxes using the EAC, follow the below process:<\/p>