Update: Tonight (May 14, 2008) at 10:00PM CST we will be implementing the new filter via Postini. You will not lose any email and should not see any downtime in your service.
We have noticed that Non-Delivery Receipts (NDR) messages have been flooding users inboxes, sometimes at a rate of 100 or more per hour. A NDR is a message sent from a mail server when a problem occurs with delivery. Normally these are returned to the sender when you type in the wrong email address or send an email to an address or user that doesn’t exist. The increase is due to a tactic spammers are utilizing more prevalently to ’spoof’ your email address, basically making the “From” address be a real domain or sender. The result is that when a server sends a message to a user that doesn’t exist, well spoofing your email address, the recipient email server sends a NDR back to the spoofed email address. When a spammer sends our tens of thousands of emails at a time, the quantity of email bounces increases.
This does not mean you have sent bad emails, only that someone ’spoofed’ your address.
We are currently working with Postini for a solution to this and expect to have it in place within the next week or so. We appreciate your patience and understanding as we fight the ever lasting battle against spam. If you have any questions, please feel free to contact us at firstname.lastname@example.org or call toll free at 1-800-747-3399.