You might find that you have a user whose mailbox keeps filling up and you need to increase the mailbox size. This guide shows you how to achieve this.


  • Open up the Exchange Management Console.
  • Expand Recipient Configuration.
  • Click Mailbox.
  • On the right-hand side click the mailbox you want to increase the size on.


  • Step 1 -> Right-click the user account.
  • Step 2 -> Click Properties.


  • Step 1 -> Click the Mailbox Settings Tab.
  • Step 2 -> Click Storage Quotas.
  • Step 3 -> Click Properties.


  • As you can see the mailbox is using the defaults set on the Database.


  • To Modify the settings, uncheck the box “Use Mailbox Database defaults.
  • Enter in the new values by selecting each checkbox.
  • Once complete click OK.
  • Back at the main mailbox properties window for the user, click Apply and then OK. Wait for replication to take place.