I have recently (tried to) send e-mails to all users.
There were a large number of bounced messages. Please note that you can update your own e-mail address using the Profile tab, the Account Related Settings and then change your e-mail address.
Those accounts that gave a bounce message and have not been on the system for over half a year, are being deleted (so that we do not keep trying to send mails to these people).
At the next bounce of a mail, the account will be deleted more quickly. So please keep your e-mail (and other address details) up to date!
Peter