John Fitzgibbon

John Fitzgibbon

Software Engineer
Joined on July 8, 2003
Total Post Views: 44,510


John Fitzgibbon is a software engineer who lives and works in San Francisco, Calif. He is employed by Shenick Software Systems, writing TCP/IP test software for network test appliances. He spends way too much of his spare time devising filters for spam.

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Fight Spam With the DNS, Not the CIA

It seems like spam is in the news every day lately, and frankly, some of the proposed solutions seem either completely hare-brained or worse than the problem itself. I'd like to reiterate a relatively modest proposal I first made over a year ago: Require legitimate DNS MX records for all outbound email servers.

MX records are one component of a domain's Domain Name System (DNS) information. They identify IP addresses that accept inbound email for a particular domain name. To get mail to, say,, a mail server picks an MX record from's DNS information and attempts to deliver the mail to that IP address. If the delivery fails because a server is out of action, the delivering server may work through the domain's MX records until it finds a server that can accept the mail. Without at least one MX record, mail cannot be delivered to a domain.

Topic Interests

DNS IPv4 MarketsDomain NamesCybersecuritySpamICANNEmailThreat Intelligence

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Fight Spam With the DNS, Not the CIA