Backscatter (E-Mail)

Backscatter ( originally a term from physics, see backscatter) in emails is backscattering by Delivery Status Notifications, which respond to forged sender addresses.

The notifications automatically sent does not go doing the actual senders to, but which or the bystanders who were indicated as the sender. These are error messages that you have written address does not exist, that the received e -mail was spam, or that the email contained malware. The latter in particular as well as the potentially large number of such mails unsettled the receiver.

Remedy

Mail Server

Today Delivery Status Notifications are typically sent only to addresses that are authenticated using SMTP Auth. Preferably, the Mail Transfer Agent will stop receiving from an early stage, so that no downstream notification is required.

There are companies that specifically look for mail gateways that allow backscatter without checking the authentication. This then land on a "black list".

Configuring the Domain

Backscatter is facilitated if catch-all email addresses for any (not only for explicitly named ) are accepted addresses of a domain and they will only then passed spam filters. If the mail transfer agent instead informed of the addresses of its domain and interactively co-operates with a virus scanner and a spam filter, backscatter can be avoided by not actually existing addresses. The Catch-All function can be configured in the rule of the domain owner.