// File pulled from BBS Knowledgebase //

Microsoft offers multiple plans for Office 365, and the mailbox size limit
varies according to the plan. For example, the E1 plan has a maximum size
limit of 50 GB for every mailbox, whereas E5 provides a size limit of 100 GB.

Thus, when the mailbox size of your mailboxes exceeds 50 GB, the
organization has only two options left - either upgrade the Office 365
subscription or delete data from the mailbox. But, deleting data is not
always an option for many. Also, not every user wants to invest in upgrading
the plan due to higher costs.

Increase Office 365 Mailbox Size using PowerShell

One way to increase the mailbox size limit is by using Exchange PowerShell
cmdlets. But, for that, you need to run PowerShell as administrator and
connect to Exchange Online (Office 365) with Windows PowerShell.

Increasing Single User Mailbox Size Limit

First, connect to Exchange Online and run PowerShell. Use the below command to
increase single user mailbox size.

>> Set-Mailbox <UserID> -ProhibitSendQuota <Value>
-ProhibitSendReceiveQuota <Value> -IssueWarningQuota <Value>

Here the parameters <UserID> represents user's mailbox or email address,
<Value> represents the sizes in GB, MB, or KB.

So, to set the mailbox size limit to 100 GB, you can set the send limit at
99 GB.

Now, use the following command to check the size of the mailbox.
>> Get-Mailbox <UserID> | Select *quota

That's how you can extend the limit for single user mailbox in Exchange
Online. If you want to increase the mailbox size for multiple users, then
follow the below steps.

Increasing Mailbox Size Limit for Multiple Users

To increase the size of multiple user mailboxes, connect to Exchange Online
and use the below command in Windows PowerShell.

>> Get-Mailbox | Set-Mailbox -ProhibitSendQuota <Value>
-ProhibitSendReceiveQuota <Value> -IssueWarningQuota <Value>

You can also apply additional filters to the Get-Mailbox cmdlet. Below is an
example that shows how you can filter on the cmdlets.

>> Get-User | where {$_. Department -eq "Sales"} | Get-Mailbox | Set-Mailbox
-ProhibitSendQuota <Value> -ProhibitSendReceiveQuota <Value>
-IssueWarningQuota <Value>

In this example, three cmdlets are used to filter the commands of an
organization's sales department. The "Where" parameters define the
department where the changes will be implemented, "ProhibitSendQuota"
parameter defines the set quota limit for a user mailbox, and the
"IssueWarningQuota" defines when a user will receive the exceed mailbox size
limit warning.

And, here also you can set the send limit at 99 GB.

When the mailbox size limit exceeds for Office 365 users, they start
receiving "mailbox size limit exceeded" warning. In such circumstances,
using the above PowerShell commands can be very helpful to quickly expand
the size limit of your Office 365 mailboxes.