How to set Exchange Online mailbox sizes and limits in the Office 365 environment

Introduction

This article describes how to use Exchange Online PowerShell to set Exchange Online mailbox sizes and limits in the Microsoft Office 365 environment.

To set mailbox size limits for Exchange Online mailboxes, use one of the following methods.

Connect to Exchange Online PowerShell.
Run the following PowerShell command to set the mailbox size for a single user:

Set-Mailbox < UserID > -ProhibitSendQuota < Value > -ProhibitSendReceiveQuota < Value > -IssueWarningQuota <Value>
Note In this command, the <User ID> placeholder represents a mailbox user's UPN, email address, or GUID, and the <Value> placeholder represents a number in megabytes (MB), kilobytes (KB), or gigabytes (GB). For example, to set a mailbox size to 20 GB, to set the send limit at 19 GB, and to issue a warning at 18 GB, run the following command:

Set-Mailbox JDoe@contoso.com -ProhibitSendQuota 19GB -ProhibitSendReceiveQuota 20GB -IssueWarningQuota 18GB
Check that the current list of quotas is attached to the mailbox. To do this, run the following command:
Get-Mailbox < User ID > | Select *quota

Connect to Exchange Online PowerShell.
Run the following PowerShell command to set the mailbox size for all the users in an organization:
Get-Mailbox | Set-Mailbox -ProhibitSendQuota < Value > -ProhibitSendReceiveQuota < Value > -IssueWarningQuota < Value > Additional filters can be applied to the Get-Mailbox cmdlet or to the Get-User cmdlet to control the users for whom the change is applied. The following is an example in which three cmdlets are used to filter the command to the sales department of an organization:
Get-User | where {$_.Department -eq "Sales"} | Get-Mailbox | Set-Mailbox -ProhibitSendQuota < Value > -ProhibitSendReceiveQuota < Value > -IssueWarningQuota < Value >

To view the current size of an Office 365 group mailbox and increase its quota, follow these steps:

Connect to Exchange Online PowerShell.
Run the following PowerShell command to view the current size of the Office 365 Group mailbox.

To view a specific group mailbox:

Get-Mailbox -GroupMailbox <name of the group> | Get-MailboxStatistics | fl TotalDeletedItemSize,TotalItemSize

To view all group mailboxes:

Get-Mailbox -GroupMailbox  -ResultSize unlimited | Get-MailboxStatistics | ft DisplayName,TotalDeletedItemSize,TotalItemSize

For more information about mailbox size limits in Exchange Online, see Mailbox storage limits.

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