you can change your quota to unlimited. Just remember that each mail file counts towards your allowed max. files for your account. eventually you will want to clean out your saved emails.
http:///www. (yourdomain) .com/webmail
You can go into webmail and sort by file size and have it display 100 or so emails at a time and delete the largest files.
You can sort by date - oldest first and delete the oldest.
You can search for email addresses that send a lot of email to you: e.g facebook, groups you belong to, family, etc.
My life can be summed up in one word, "indescribable".