When your mailbox gets close to its maximum size (300Mb for staff and 50Mb for students) you will receive a System Administrator message advising you that it is getting too full. You need to remove items from email folders to reduce the size of your mailbox back to below the quota set out above. The first place to look is your "Deleted Items" folder which is where mail initially goes when you delete it from the Inbox. Right click on the "Deleted Items" folder (position the mouse over the folder and click the right hand button) and select the "Empty Deleted Items" option from the pop-up menu. If that does not free up enough space then consider deleting some messages from your Inbox or other folders then emptying "Deleted Items" again. If the mailbox is left unattended, the system will initially stop you sending mail and finally stop you receiving mail.