Allocating your quota
Part of your personal file space (disk quota) is reserved for email. You can use the Quota Allocation tool to increase your email space and to monitor its usage. Delete or archive messages as needed to stay within your quota and avoid interrupting your email service.
Your email Trash folder or the folder you have designated for spam may fill up and exceed your email quota. If this happens, your email program may or may not warn you, but you will stop receiving new messages, though you should still be able to send messages. If you've missed receiving a message because your storage space is full, the system will keep trying to send it to you at 30-minute intervals for up to three days. If your space has been full continuously for 30 days or more, the system will return the message immediately and advise the sender that your account is not being used. To correct the situation, you will need to free up space as indicated in Exceeding Email Quota.
You may need to keep some email messages indefinitely. If so, you will have to store them on your hard drive or a removeable medium such as CD. If you are using Webmail, see the procedure for Archiving Messages in Webmail.
For additional tips, see the page on Using Email Efficiently.