From Fermilab Today, August 18, 2009
Starting today, requirements have changed for new passwords on IMAP server e-mail accounts. When you reset your IMAP server e-mail account password, your new password will need to be at least 10 characters long in order to fulfill Department of Energy password complexity requirements.
Strong passwords include a combination of letters, symbols and numbers. For instructions on how to change your IMAP password, see this site.
On Sept. 15, all IMAP users who have not already chosen a new, 10-character password will be required to reset their passwords using the new requirements.