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How to Increase Office 365 Mailbox Size in 2021?

Lindsey Smith ~ Published: February 3, 2021 ~ 4 Minutes Reading

Summary: Have you ever encountered the Office 365 Mailbox Size Exceeded alert? If this happens with you, then your mailbox has either stopped bringing in new mails or will soon cease to. Keep on reading to know how to deal with this problem and learn ways to increase office 365 mailbox size.

Microsoft offers various plans for Office 365. The size of their mailboxes differs as per the plan you have subscribed to. As most of the users prefer storing their data on cloud platforms, more space is required.

Some plans offer 50 GB, while others like Enterprise E5 offers 100 GB of storage space. So how can you increase Office 365 mailbox size to 100GB? You are left with two options here. One is to upgrade your plan and the other one is to delete your mailbox data items.

“I have a subscription plan of O365 business premium which offers only 50 GB space. But now after having consumed every bit of it, I need more cloud storage to continue my work. How can I get rid of the Office 365 mailbox size exceeded error?”

How to Increase Office 365 Mailbox Size to 100 GB?

The easiest method is to delete the unwanted items from your account. You can delete documents, emails, etc. that you do not need anymore. But before doing that, you must create a local Office 365 backup on your computer for future use.

Backing up your data is essential to protect it against any ransomware attacks or accidental deletion. You can always access your data even during the downtime of servers. As Microsoft does not take the responsibility of protecting your data, you completely have to secure it.

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This is one such software that is used by the majority of businesses to secure their data. With its help, you can always restore the data into your Office 365 account. After creating a copy of your crucial data, you can use the Powershell commands to fix the Office 365 mailbox size exceeded error.

How to Increase Office 365 Mailbox Size Using Powershell?

Windows Powershell commands are a powerful utility to help you increase the size. Follow the below-given methods to fix the error:

Set mailbox size limits:

Steps For Single User to Increase Office 365 Mailbox Size:

  1. First, connect to Exchange Online using remote Powershell.
  2. Now, run the following command to upgrade Office 365 Mailbox Size for a single user.

Note: The placeholder GUID, email address, or UPN of the mailbox user. Whereas, the placeholder represents numbers in MB, GB, KB.

3. Next, you must check whether the current list of quotas is attached to the mailbox or not. To increase Office 365 mailbox size, execute the following command.


Steps For Multiple Users to Increase Office 365 Mailbox Size:

  1. Connect to the Exchange Online using the remote PowerShell.
  2. To set the mailbox size limits for all users in an organization, run the following command.

Note: You can also apply filters to the Get-User cmdlet or Get-Mailbox cmdlet to control the user for whom you have applied these changes.

Let’s execute this command in the Finance department of any organization.


The above method works wonders to deal with the Office 365 Mailbox Size Exceeded alert message. You should use these steps very carefully, as these are technical cmdlets scripts, and a minor error in the scripts can result in severe crucial data loss.

Hence It is always recommended to take a backup of your existing data in Office 365, just in case you mess up something then a copy of your entire mailbox would be ready with you.


In this blog, you have learned about how to increase Office 365 mailbox size in detail. I hope you will be able to resolve this issue after following the above-given methods.

To summarize, we provided you foolproof methods to help you solve the Office 365 mailbox size exceeded error. Follow the steps and do not forget to take a backup in case something goes wrong. Above mentioned software is a brilliant solution for creating a local backup of your existing data in Office 365.