Thursday, February 08, 2007

Fight spam with "no listing"

Usually, when you create MX records for your organization, the lowest MX record points to the server that always accepts mail for your organization and the higher ones are the backups. If your primary fails, SMTP clients roll over to a secondary.

I recently read about a concept called "no listing or nolisting" and thought it was blogworthy. You create the lowest MX record and have it point to nothing, then the second highest points to a valid SMTP server. The premise is that spam 'bots and zombies are not smart enough to try the secondary MX records and thus they skip your domain.

I have not tried this yet, but it sounds like an interesting concept. You can read more about this here: "Nolisting: Poor Man's Greylisting"



At 11:34 AM, Blogger Computer said...


As far as I know professional spam servers target lower priority MX records specifically so that might not be a good idea. Some folks even want to dump "secondary/backup" MX records for that reason ...


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