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Staying off the Blacklist

In my last post I mentioned how setting up a Feedback loop can help you keep track of spam reports for your server. I realized that it helped tackle only a small portion of the problems faced by Webhosts when it comes to email blacklists. So in this post we’ll take a deeper look at what a Blacklist is, how you can use it and you can avoid getting your own IPs on a Blacklist.

What are email Blacklists?

As the name suggests, an email blacklist contains a list of IPs that have been reported to be a source of spam. Most blacklist authorities implement what is called a DNSBL – DNS-based Black List. This is similar to a the normal DNS, only instead of querying to get the IP address of a domain name, we query the DNSBL to see if an IP address is on that list. It returns details as to why the IP address is listed on that Blacklist, usually including a URL that can be visited to get more details.