PowerShell command.
Example box – Something@something.com (don’t include domain @something.com)
Get-MailboxFolderStatistics -Identity Something
| Feature | Office 365 Business Essentials | Office 365 Business Premium | Office 365 Education | Office 365 Enterprise E1 | Office 365 Enterprise E3 | Office 365 Enterprise E5 | Office 365 Enterprise K1 |
| Maximum number of messages per mailbox folder | 1 million | 1 million | 1 million | 1 million | 1 million | 1 million | 1 million |
| Warning for number of messages per mailbox folder | 900,000 | 900,000 | 900,000 | 900,000 | 900,000 | 900,000 | 900,000 |
| Maximum number of messages per folder in the Recoverable Items folder | 3 million | 3 million | 3 million | 3 million | 3 million | 3 million | 3 million |
| Storage quota for Recoverable Items folder in primary mailbox (not on hold) | 30 GB | 30 GB | 30 GB | 30 GB | 30 GB | 30 GB | 30 GB |
| Storage quota for Recoverable Items folder in primary mailbox (on hold) | 100 GB | 100 GB | 100 GB | 100 GB | 100 GB | 100 GB | 100 GB |
| Storage quota for Recoverable Items folder in archive mailbox (not on hold) | 30 GB | 30 GB | Unlimited2 | 30 GB | Unlimited2 | Unlimited2 | 30 GB |
| Storage quota for Recoverable Items folder in archive mailbox (on hold) | 100 GB1 | 100 GB1 | Unlimited2 | 100 GB1 | Unlimited2 | Unlimited2 | 100 GB1 |
| Warning for number of messages per folder in the Recoverable Items folder | 2.75 million | 2.75 million | 2.75 million | 2.75 million | 2.75 million | 2.75 million | 2.75 million |
| Maximum number of subfolders per mailbox folder | 10,000 | 10,000 | 10,000 | 10,000 | 10,000 | 10,000 | 10,000 |
| Warning for number of subfolders per mailbox folder | 9000 | 9000 | 9000 | 9000 | 9000 | 9000 | 9000 |
| Maximum folder hierarchy depth | 300 | 300 | 300 | 300 | 300 | 300 | 300 |
| Warning for folder hierarchy depth | 250 | 250 | 250 | 250 | 250 | 250 | 250 |
| Maximum number of public folders | 100,000 | 100,000 | 100,000 | 100,000 | 100,000 | 100,000 | Not available |
| Maximum number of subfolders per public folder | 10,000 | 10,000 | 10,000 | 10,000 | 10,000 | 10,000 | Not available |
| Warning for number of subfolders per public folder | 9000 | 9000 | 9000 | 9000 | 9000 | 9000 | Not available |
1 This is the storage quota for the Recoverable Items folder, not the quota for the entire archive mailbox. The storage quota for the archive mailbox is unlimited for users with an Exchange Online (Plan 2) license or for users who have both an Exchange Online Plan 1 and an Exchange Online Archiving license. For information about increasing the Recoverable Items quota, see Increase the Recoverable Items quota for mailboxes on hold.
2 The initial storage quota for the Recoverable Items folder in an archive mailbox is 100 GB. When auto-expanding archiving is turned on, additional storage is automatically added when the storage capacity for the Recoverable Items folder is reached. For more information, see Overview of unlimited archiving in Office 365. See the Office 365 Roadmap for details about availability of auto-expanding archiving.
Posted by 
Not Just SharePoint 