Spam Trap

What is a spam trap?

A spam trap is an email address that exists to catch senders who don't have permission to email the people on their list.

Nobody reads a spam trap. It never signs up for anything, never opens and never clicks. So if your emails are landing in one, it's a strong sign that the address got onto your list in a way it shouldn't have.

Spam traps are run by blocklist operators like Spamhaus and by inbox providers. Hitting them can get your sending domain or IP added to a blacklist, which means many inboxes will start rejecting your emails or sending them to spam.

Types of spam trap

There are three main kinds:

1. Pristine traps. Addresses that have never belonged to a real person. They're published or hidden on websites where only scrapers would find them, so they end up on bought, rented and harvested lists.
2. Recycled traps. Real addresses that were abandoned, then switched back on as traps. Spamhaus notes that mailboxes left inactive for more than 12 months can be turned into spam traps.
3. Typo traps. Addresses at misspelt domains, like name@gmial.com. These usually arrive through sign-up forms without any confirmation step.

How do you avoid spam traps?

You can't see which addresses are traps, so you can't simply delete them. The fix is to stop them getting on your list in the first place:

• Never buy, rent or harvest lists. Spamhaus says these are the most common source of spam trap hits.
• Use double opt-in. A trap can't click a confirmation link, so it never makes it onto your list.
• Sunset inactive contacts. Send a re-engagement email, then stop emailing people who don't respond. This keeps recycled traps off your list.
• Remove hard bounces straight away. An address that bounces today could be a trap next year.

List-checking tools aren't a substitute for permission. Spamhaus is clear that you should fix where bad addresses come from, rather than try to clean them out afterwards.

Example

A charity imports a spreadsheet of contacts from an event they ran in 2019. Many of those people haven't heard from the charity in years, and some of their addresses have since been abandoned and converted into recycled spam traps.

The charity's next newsletter hits several of them, and their sending domain is added to a blocklist. Their delivery rate drops across every inbox provider that checks it.

Had they confirmed each contact's permission first, or re-engaged the list before sending, the traps would never have been emailed.

Read more in What Spamhaus wants from your emails.