One way to keep spam traps off your list

Having spam traps on your email list causes a world of problems: listings on commonly used blacklists and blocks at top ISPs. For the uninitiated, a spam trap is usually an address that was created new and never signed up to receive any mailings. Therefore, by definition, all mail going to that account is unsolicited. This is a great tool to catch spammers who will often mail to addresses that they have harvested from web sites and newsgroups where the good folks who run the spam trap network have published their spam trap email addresses.

So how do legitimate marketers get spam traps on their lists? In our experience, there are three primary ways: (1) Bad luck – when entering an email address in a signup form, the user makes a typo and suddenly you’re a proud owner of a spam trap address; (2) Bad partners – one of your data partners (co-registration, etc.) sent you some spam traps; (3) Bad actors – someone harvested a lot of addresses and bulk added them to your list. There are other ways, but this is what we see most frequently.

Once a spam trap gets on you list, it’s really hard to root them out. The operators of the networks are understandably reluctant to tell you exactly which address is a trap. The best approach is to not add trap addresses to your list in the first place. There are a variety of ways to do this. It goes without saying that the *best* way to prevent spam traps is to use confirmed (“double”) opt-in. However, this doesn’t work for some of our clients. One method that we’ve been working with some of our clients is quarantine approach. Here’s how it works:

* Set up a IP address that sends newly acquired addresses that were acquired on a given day. Let’s call those addresses that come in on that day a “cohort.”
* Mail a given “cohort” from that IP address for a few days.
* Review to see whether that IP has been listed as having spam traps at a few sources of spam trap data that are public – the Spam Cop blacklist and Microsoft’s SNDS service are two good places to start. Ideally, this list should be as large as possible.
* If after three days you don’t see any spam trap hits from this IP, the list is likely clean and you can put this “cohort” into your main IP pool.

This appears to be working well so far. I’d be curious to hear if anyone else has tried this (or other techniques) and see what the results are. Email me if you have stories.

One other thing to note: some ISPs are now using abandoned addresses as spam traps, as well. The best way to keep those off your list is to run your list through list hygiene and ECOA often, and to set up an algorithm to remove non-responders after a given period of time.

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