What is a spam trap?

A spam trap is an email address that doesn’t belong to a real subscriber or recipient, which means no one actually signed the address up for email. Internet service providers (ISPs) and Email service providers (ESPs) create spam traps to lure or identify spam, in order to pinpoint email senders with poor data hygiene or address collection practices. Sending email to spam traps will lower a sender’s reputation and can result in reduced delivery rates or even blacklisting.


Are there different types of spam traps?


There are three types of spam traps to be aware of: pristine spam traps, recycled or grey spam traps, and typo spam traps.


  • Pristine spam traps are email addresses created by ISPs/ESPs specifically to catch spam. They have never belonged to a subscriber and won’t be used to sign up for legitimate email. These addresses are placed on the Internet in locations that can only be obtained by programs looking to harvest email addresses.

  • Recycled or grey spam traps are addresses that once belonged to a real subscriber, who has since shut down the address or left the service. After a period of inactivity, the ISP/ESP turns the old email address into a spam trap.

  • Typo spam traps are email addresses set up as variations of real addresses or domains – like gmial.com or yahoo.cmo. People signing up for email could theoretically type these, but they won’t actually interact with email sent to the address.



How do spam traps work?


In some cases, ISPs and ESPs put spam trap addresses on the Internet to be picked up by email address ‘harvesters.’


An ISP or ESP can tell when a spam trap address receives mail. If a pristine spam trap receives email, the ISP/ESP determines that the sender obtained the email address in a non-organic way (from another system, from another provider, a purchased list, etc.) because that email address is not actually used by a human being.


If a recycled spam trap receives email, it may mean that the address was obtained non-organically. However, it is more likely to mean that the subscriber who once owned the address signed up for something, but has long moved on – indicating that the emailer doesn’t clean up their lists to remove inactive subscribers.


If a typo spam trap receives email, it means the emailer doesn’t verify the addresses people sign up with, such as with a ‘welcome’ email, and that they aren’t cleaning up their lists of non-responders and inactive subscribers.


What are the risks or penalties for sending to spam traps?


The more spam traps emailers send to, the lower their sender reputation. They may find that ISPs/ESPs accept less of their email, deliver more of it to spam folders, and possibly blacklist their IP addresses.


How does Questline encourage clients to avoid spam traps?


We always encourage clients to grow lists organically, as using purchased email lists is very likely to damage reputation and deliverability. But maintaining a clean subscriber list after people sign up is equally important. 


After verifying email addresses up front when obtaining subscribers – by using an email Welcome Series, for example – clients should regularly search for and remove inactive/unengaged subscribers. Spam trap addresses won’t ever have opens or clicks; there will be no engagement with communications sent to them. And just as it’s best practice to remove inactive subscribers to improve ISP/ESP reputation, it’s also a good way to get rid of spam traps.


How do we know we’re hitting spam traps?


Questline’s deliverability metrics and insights provide us with information about what IP addresses, what campaigns and even what sends are hitting spam traps. The ISPs and ESPs pass this information on to us, with the hope that we’ll perform list hygiene. We can tell which Questline clients are hitting spam traps regularly.


So if we know that, don’t we know the spam trap addresses? Can’t we just remove them?


We know what sends are hitting spam traps, but the ISPs/ESPs don’t tell us what actual addresses on our lists are spam traps. This keeps the spam traps valid for reuse. Once an email address is officially known to be a spam trap, it’s no longer useful. Plus, the ISPs and ESPs don’t want to do our work for us – they want to encourage us to use email list hygiene best practices.