One of the primary duties of the Administrator is to monitor the size of your users’ mailboxes to ensure that
they do not exceed the size limit on the server. Once the mailbox limit has been exceeded by approximately
five percent (5.0%), the communication to the Exchange mailbox will shut down and the users will no longer
be able to send or receive email. Users receive an Exchange system notification email when their mailboxes
reach a pre-defined “warning limit” that the mailbox is approaching capacity. Upon receiving such a warning,
the mailbox needs to be managed by either utilizing the archiving features of Outlook or Entourage, or by
increasing the mailbox size.
Administrators should routinely access the Storage Usage Report in order to remain aware of users’ mailbox
size limits and usage in order to effectively manage the total allocated storage space.
1. Log into the Control Panel.
2. Select the Mailboxes shortcut from the Exchange section of the main dashboard.
3. Select the mailbox in the list for which you wish to adjust the mailbox size by clicking the appropriate
4. Select the Limits tab:
Notice the Mailbox Size fields in the top half of the screen.
5. On the Limits tab, click the [Edit] button to access editable mailbox size information:
6. Change the Mailbox Size limits as necessary:
• Issue warning at: When the mailbox reaches this size, the system notification warning email is sent
to the user to indicate that the mailbox is approaching its capacity prior to being locked down. For a
typical 5 GB mailbox, we advise setting this value at 500 MB less than the actual size of the mailbox in
order to provide adequate warning for the mailbox size to be adjusted.
• Prohibit send at: We advise admins to set this value to 250 MB less than the actual mailbox size.
When this limit is reached, the user will no longer be able to send email, though if the mailbox still
has capacity the user will continue to receive email. This limit is utilized for users who routinely send
large attachments in order to avoid accidently locking down the mailbox due to sending a large email
when nearing mailbox capacity.
• Size limit: This represents the actual capacity of the mailbox. Base the other two inputs above upon
the value set here as the mailbox capacity.
7. Click [Submit] when finished.
Changes display on the Limits tab.
8. You may click the [Update Size] button to refresh the Mailbox Size information.