IMF-Bounces * BACKCLICK includes an intelligent mail filter (IMF). This filter manages the “Bounces” — e-mails sent back to the sending server from the receiving server after a newsletter has been sent. Bounces are divided into “Soft Bounces” and “Hard Bounces.” Soft Bounces occur when a successful delivery is temporarily impossible, often because the recipient’s mailbox is full. Hard Bounces take place if delivery is completely impossible, most likely because the recipient’s address is incorrect or invalid. The IMF reacts to a Hard Bounce by deleting the recipient from the subscriber database. For a Soft Bounce, it will try to deliver the e-mail again. The IMF can also react to manually returned e-mails. These e-mails will appear if (for example) a subscriber responds to a newsletter by sending an e-mail. These manually returned e-mails are checked according to the rules of Bayes’ filters, and then presorted into a corresponding category.