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Liam McLennan hackingon.net
Last friday morning I began to receive hundreds of delivery failure email messages. This is a common problem that can be difficult to solve. It happened because a spammer began using my email address as the FROM address for their spam messages. Because the spam gets sent to a huge number of non-existant email addresses I received a corresponding number of delivery failure messages.

According to Wikipedia, "SPF allows software to identify and reject forged addresses in the SMTP MAIL FROM (Return-Path), a typical nuisance in e-mail spam". To setup SPF you have to add a special record to your domains DNS that defines the valid email servers for that domain. All other senders become invalid. For help with the syntax of the SPF record I used the tools on the open spf web site (http://old.openspf.org/wizard.html). For my domain, eclipsewebsolutions.com.au, the SPF record is v=spf1 a mx ~all. This string informs mail servers that only my server is allowed to send email for my domain. Within hours the delivery failure messages began to slow down, and forty-eight hours later they had nearly stopped.

SPF helped me to avoid a disaster that could have resulted in the need to abandon my email address and reprint all my stationary. Posted on Sunday, May 11, 2008 3:45 PM | Back to top

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