In Exchange, storage quotas allow messaging administrators to control the size of mailboxes and manage the growth of mailbox databases. As storage is cheap these days, many organizations decide not to put any limits on mailbox storage sizes. This can cause the mailbox database sizes to balloon to unmanageable sizes, thus causing long backup and restore times, sometimes failure of backups, long and unfinished online maintenance and takes ridiculous amounts of time to perform any offline maintenance.
It is highly recommended to place mailbox storage quotas on all new deployments of Exchange to avoid these issues. Quota limits can always be changed on individual mailboxes that may require additional storage sizes. The following limits can be placed on mailbox databases:
- Issue warning at (KB) Use to specify the maximum storage limit in kilobytes (KB) before a warning is issued to the mailbox user. The value range is from 0 through 2,147,483,647 KB. If the mailbox size reaches or exceeds the value specified, Exchange sends a warning message to the mailbox user
- Prohibit send at (KB) Use to specify a prohibit send limit in KB for the mailbox. The value range is from 0 through 2,147,483,647 KB. If the mailbox size reaches or exceeds the specified limit, Exchange prevents the mailbox user from sending new messages and displays a descriptive error message
- Prohibit send and receive at (KB) Use to specify a prohibit send and receive limit in KB for the mailbox. The value range is from 0 through 2,147,483,647 KB. If the mailbox size reaches or exceeds the specified limit, Exchange prevents the mailbox user from sending new messages and won’t deliver any new messages to the mailbox. Any messages sent to the mailbox are returned to the sender with a descriptive error message
It is usually the case that users will ignore such warning messages and will attempt to contact administrators when their mailboxes cannot send or receive emails anymore. To workaround this, monitoring applications can be used to monitor the sizes of the mailboxes and notification sent to administrators. For those organizations that do not have any monitoring applications, Exchange transport rules can be used.
A quota message is an e-mail message that’s automatically sent by Microsoft Exchange to the owners of a mailbox when a size limit (called a storage quota) for the mailbox is exceeded. 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. The table below shows the mailbox quota messages sent by exchange
|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 warningquota
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.|
For an administrator to receive the quota messages as well, create a transport rule using the following steps:
- Navigate to Organization Configuration > Hub Transport. In the result pane, click the Transport Rules tab. In the action pane, click New Transport Rule
- On the Introduction page, provide a meaningful name for the rule and enter a descriptive comment (highly recommended) for the rule so other administrators know the function of it. The Enable Rule checkbox is selected by default – do not change it
- On the Conditions page, complete the following fields. In the Step 1. Select condition(s) box select When the Subject field contains specific words.
- This selected conditions requires additional value so in the Step 2. Edit the rule description by clicking an underlined value box, click the blue underlined word.
- Enter your mailbox is as the words, click Add then OK to return to the wizard. Click Next to continue
- On the Actions page, in the Step 1. Select actions box, select Blind carbon copy (Bcc) the message to addresses as the action to take.
- Click the blue underlined word and enter the address of the administrator (or the address of a distribution group containing multiple administrators). Once added click OK then. After you configure all the actions, click Next
- On the Exceptions page, no changes were made so click Next to continue
- On the Create Rule page, review the Configuration Summary. If you’re satisfied with the configuration of the new rule, click New
- On the Completion page, review the following, and then click Finish to close the wizard:
- A status of Completed indicates that the wizard completed the task successfully.
- A status of Failed indicates that the task wasn’t completed. If the task fails, review the summary for an explanation and then click Back to make any configuration changes.