Exchange 2010 SP1 introduces a flag that controls whether a mailbox is checked to see if its size is equal to or greater than 50% of the Prohibit send quota.As a result, if the Issue Warning quota is set to a value less than 50% of the Prohibit send quota, the warning message associated with the Issue warning quota won’t be sent to the user. For example, if a mailbox has a size limit of 10 MB, and you set the Issue warning quota to 3 MB and the Prohibit send quota to 8 MB, the user won’t ever receive the warning specified by the Issue warning quota because the Issue warning quota limit isn’t equal to or greater than 50% of the Prohibit send quota. Instead, the user will receive only the message associated with the Prohibit send quota (in this case, when the user’s mailbox size reaches 8 MB).

In addition, the flag is cleared after you run the Set-MailboxDatabase cmdlet with the QuotaNotificationSchedule parameter. When you run that command, the mailbox won’t be checked again until the flag is reset. Flags are reset when a message is saved in the mailbox or when a message is sent to or from the mailbox.At that point if the mailbox size is greater than 50% of the Prohibit send quota, the flag is reset and the mailbox is checked at the time specified by the QuotaNotificationSchedule parameter.

A storage quota is a storage size limit for a mailbox or a public folder. You can use the Exchange Management Console (EMC) or the Shell to view or set the storage quotas for all of the mailboxes or public folders in a database. You can also use the EMC or the Shell to set storage quotas on a per-mailbox basis, thereby overriding the storage quotas that are set at the database level. However, storage quotas for individual public folders can be viewed or set only in the Shell.

For more information about viewing and configuring storage quotas, see the following topics:

• Configure Mailbox Database Properties
  
  
• Configure Storage Quotas for a Mailbox
  
  
• Configure Archive Quotas for a Personal (On-Premises) Archive
  
  
• Set-MailboxDatabase
  
  
• Set-Mailbox
  
  
• Configure Public Folder Properties
  
  
• Set-PublicFolderDatabase
  
  
• Set-PublicFolder
  
  

By default, Exchange sends a quota message to mailbox or public folder owners when a:

• Mailbox, personal archive, or public folder exceeds its Issue warning limit (the lowest storage quota).
  
  
• Mailbox exceeds its Prohibit send limit or a public folder exceeds its Prohibit post limit (the middle storage quota).
  
  
• Mailbox exceeds its Prohibit send and receive quota or a personal archive exceeds its archive quota (the highest storage quota).
  
  

Quota messages for mailboxes are sent to mailbox owners. If a mailbox is owned by a security group (that is, if it's a shared mailbox), quota messages are sent to the security group. Quota messages for public folders are sent to every public folder owner. Owners of mailboxes and public folders can be users, contacts, or security groups.

Quota messages are sent with high importance and aren't subject to storage quotas. They're always delivered, even if the recipient's mailbox is full.

Exchange can generate quota messages in many languages. For a list of the supported language locales that are available for use with quota messages, see Supported Locales for Use with System Messages.

Quota Message Format

Default Quota Messages

The following tables list the subject and the default message text for the seven default English quota messages (four for mailboxes and three for public folders). The default message can be customized, but the subject text can't.

Note:
There are no specific archive quota messages. If a user's archive is meeting or exceeding any quotas, they will receive mailbox quota messages.

Mailbox quota and archive quota messages

Event	Subject of message	Default message text
Mailbox of unlimited size exceeds its Issue warning quota	Your mailbox is becoming too large	Please reduce your mailbox size. Delete any items you don't need from your mailbox and empty your Deleted Items folder.
Mailbox of limited size exceeds its Issue warning quota Important: The message associated with the Issue warning quota won’t be sent to the user unless the value of the quota is greater than 50% of the value specified in the Prohibit send quota. For example, if you set the Prohibit send quota to 8 MB, you must set the Issue warning quota to at least 4 MB. If you don’t, the Issue warning quota message won’t be sent.	Your mailbox is almost full	Please reduce your mailbox size. Delete any items you don't need from your mailbox and empty your Deleted Items folder.
Mailbox of limited size exceeds its Prohibit send quota	Your mailbox is full	Your mailbox can no longer send messages. Please reduce your mailbox size. Delete any items you don't need from your mailbox and empty your Deleted Items folder.
Mailbox of limited size exceeds its Prohibit send and receive quota	Your mailbox is full	Your mailbox can no longer send or receive messages. Please reduce your mailbox size. Delete any items you don't need from your mailbox and empty your Deleted Items folder.

Public folder quota messages

Event	Subject of message	Default message text
Public folder of unlimited size exceeds its Issue warning quota	Your public folder is becoming too large	Please reduce the size of your public folder by deleting any items you don't need.
Public folder of limited size exceeds its Issue warning quota	Your public folder is almost full	Please reduce the size of your public folder by deleting any items you don't need.
Public folder of limited size exceeds its Prohibit post quota	Your public folder is full	Users can no longer post items to this folder. Please reduce the size of your public folder by deleting any items you don't need.