Blue Utopia Blog

Blacklists and Spamtraps and how to avoid them

Tue, May 25, 2021 - 01:40 PM

in Email Outreach

What are spam traps?

Spam traps are fake or historical email addresses that are used by Email Service Providers (ESPs) and blacklist providers to identify bad email senders.

A spam trap is essentially just an email address but it's not owned by a real person. Because it's not a legitimately-owned email, it cannot opt-in to receive email and is not ever used in the process of real email communication between sender and recipient.

Because of this blacklist providers use these spamtraps to identify bad email senders. Then ESP's use those blacklists to filter out emails from these senders, who send to spamtraps.

How many types of spamtraps?

Essentially, there are three types:

Designed spam traps

These are email addresses that were originally created for the purpose of being a spamtrap. They have never been used by anyone and have never opted into an email list. By definition, if one of these email addresses is receiving an email, then it was done without signup permission.

Dormant emails

Dormant emails are very old email addresses that are no longer in use by the original owner. The address has been abandoned for so long the provider (ESP) has repurposed it as a trap to expose senders who are either not managing their email marketing program or might be borrowing badly-managed lists.

Invalid email addresses

Invalid emails can end up on your list when a visitor types in the wrong email, like instead of Similar to recycled spam traps, these addresses never open or click any of the messages they receive. Because they have a zero open rate, ESP's consider the existence of these as poor list acquisition/cleansing practices.

Damage to your email program

Getting your email flagged by blacklist providers can have a minor or quite substantial impact on your ability to have your emails delivered. Here are a couple of the more common actions to your email hitting spamtraps:

  • Your sender reputation will be damaged. This will cause higher bounce rates, as well as a higher percentage of emails going to the junk folder. Both of these can have profound effects on the effectiveness of your email being received and read.

  • The corresponding IP addresses used to send your email may be added to a blacklist database, which means deliverability for you as well as other email senders will be affected.

How to find out if you're on an email blacklist

First, find out the domain or IP from where you send email. In some cases, it may be more than one IP. In some cases, the domain is a 3rd party domain (e.g. or You can get this information from the header of an email that you have sent. Here are instructions for getting the header info from an email.

There are a lot of blacklists so checking each can take some time. Fortunately, there are a couple of places you can check all of them at once.

250K (acquired by Validity) allows you to check all of the main blocklists from one query.

MXToolBox is another great tool to show you the health of your domain or IP.

Reducing your risk of getting on an email blacklist

The three best things you can do to keep from ever hitting a spamtrap are:

  1. Never buy or borrow a list. This goes double for buying a list from a commercial email vendor as so many of the emails will be scraped from the web and/or dormant. Borrowing email lists is not a good practice as it can destroy your ability to get an email to your real supporters. Having said that, borrowing a seed list is a reality in the political space. Be cautions with this practice. Think about validating the emails from any borrowed list. Better than just borrowing a list, try having the lending campaign/pac/party send an email on your behalf instead.

  2. Use double opt-in when asking for signups on your website. This can reduce your signups just due to the extra step required but can also save you a lot of trouble with your eventual deliverability.

  3. Clean your list constantly. If an email bounces, remove it, instantly. Never send to a (hard) bounced email twice. And periodically clean your list from unresponsive recipients. Segment your list every few months into non-engaged and try to re-engage your non-active recipients. If you can't re-engage them, remove them from your active sending list.


Spamtraps serve a legitimate purpose of filtering out bad email senders, which serves to keep email an effective method of communicating with your supporters. Be super diligent if, as startup campaign, you feel like borrowing an email list. It can really limit your ability to deliver future email and it may impact others as well. Always keep your lists clean and remember - delivering to 20K inboxes is much better than getting bounced or sent to junk with a 50K send.

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