How to keep your email spam trap free

Spam traps are among the most damaging types of email addresses. While they might not be as prevalent as simple inactive mailboxes and catch-all emails, they can have a big impact on your deliverability if you send to one. And that’s because their only purpose is to catch spammers.

In this guide, we’re going to talk about what spam traps are, how they work, why they matter for transactional email, and how you can keep them out of your database and protect your email deliverability.

What are spam traps?

A spam trap is used by Internet Service Providers (ISPs), anti-spam organizations and blocklist services to catch spammers and other senders who carry out questionable sending practices. They are also known as honeypot email addresses, and they look like a normal email address.

How spam traps work

Spam traps are essentially fake email addresses. They may have even been active at some point, but because they don’t belong to a real person, if you send to one, it tells ISPs a few things. 

• You purchased an email list,

• You scraped the email address from the web,

• Or you send to outdated recipients regardless of their engagement, i.e, you’re not maintaining good list hygiene

Since these indicate that, at the very least, you don’t follow sending best practices or, at worst, you’re a spammer, sending to a spam trap is likely to get your IP or domain blocklisted.

Why do spam traps matter for transactional email?

You might be thinking that, since transactional emails are triggered by recipients’ activity in your app or website, surely spam traps can’t be much of an issue. And yes, there is slightly less risk than for marketing emails, but the potential for spam traps to infiltrate your contact lists still exists. 

Some types of transactional emails (like welcome emails and onboarding emails) are sent to all signups upon registration, and others (like announcements, trial expiration notifications and maintenance alerts) are sent in bulk to all email addresses in your contact list. 

These types of messages will also be sent to any spam traps that are entered at signup or are already in your database. And since deliverability is even more crucial for transactional emails, you really don’t want this to happen! Getting caught in a spam trap can result in: 

• Your IP being blocklisted

• Damage to your sender reputation

• Emails going to the spam folder or not being delivered at all

• Pausing or termination of your account with your ESP if you violate their terms

• Disruption to the user experience (imagine password resets and other important emails not being delivered)

• Damage to your brand reputation

Types of spam traps

There are 3 types of spam traps, and you can hit them in different ways. These are pristine, recycled, and typos. 

Pristine spam traps

These are completely fake email addresses that are created purely to catch spammers and never belonged to a real user. Pristine traps typically won’t be used for signups or anything else. They are usually planted on third-party lists for sale or in the code of websites where they’ll be picked up during scraping, and won’t be visible for people to see. 

Recycled spam traps

Recycled traps are email addresses that did belong to a real person at one time. They would have been abandoned or deactivated and then reactivated by ISPs to be used as traps. 

Typo spam traps

These are spam traps that take advantage of common typos and misspellings of real, popular domains. For example, name@gnail.com instead of gmail.com.

How spam traps can enter your list of transactional email recipients

Bot activity

Bot attacks and automated submissions pose a risk because they sometimes use spam trap email addresses to sign up (you know, just to cause a little extra mayhem). They’re also becoming more sophisticated, evolving to programmatically verify email addresses to make it past this checkpoint. 

Inactive email addresses

Some spam traps were born spam traps. And others… they became inactive or were closed by their owners and then recruited by ISPs for a greater, spam-fighting purpose. So, if old users or customers don’t update their email addresses, it’s entirely possible that your customer list includes email addresses that have become inactive and have been turned into spam traps. 

Lack of email validation methods

Email validation at sign up can catch typos and email addresses with incorrect formats, preventing typo spam traps from getting to your database. Plus, there are additional email verification methods you can use to catch known spam traps and invalid email addresses. Without any kind of email validation, anything can be submitted to your recipient list, including spam traps.

How to identify spam traps

It can be tricky to identify a spam trap because they are designed to look like real email addresses. If they had very obvious traits that scream “Hey, I’m a spam trap!” they would be kind of useless. 

But there are a few signs to look out for that might indicate you’ve hit a tap, and tools you can use to check your recipient email addresses. 

Unusual metrics

If you notice a sudden drop in your open rates or click rates, it could indicate you’ve hit a spam trap, been blocklisted, or are sending to other kinds of invalid email addresses. It’s time to investigate.

High bounce rate

Not all types of spam traps will bounce—pristine spam traps usually don’t, but typo traps will. If you have a higher-than-usual bounce rate paired with a drop in engagement, it’s definitely time to clean your recipient list and check for spam traps.

Verify your recipients’ emails

An email verification service will let you submit a list of email addresses via an app or API and run various checks. These include typo and syntax checks, MX record checks, disposable domain checks, and checks for known spam traps. It will help you identify all kinds of invalid and risky email addresses so you can add them to your suppressions and exclude them from future sending.

How to avoid sending to a spam trap

The number one rule to avoid spam traps is to never buy a list of emails or scrape the web for them because you will, without doubt, hit a spam trap. But this is more of a concern for email marketing and doesn’t really apply to transactional email sending, so what else can you do?

1. Use email validation and real-time verification

Make sure that anywhere you collect email addresses from users, you implement email validation to catch typos and invalid email formats at the very least. And if you really want to keep your database clean and save yourself a lot of work further down the line, an email verification API can help you block other kinds of invalid emails too. 

We have a guide on PHP email validation, plus this guide on real-time email verification, so make sure you check those out.

2. Require users to confirm their email address

When someone signs up to your app, send them a confirmation email before they become a fully-fledged user. It’s possible that some bots will bypass this step anyway, but it’s good practice to verify users, and combined with other methods, can help prevent spam traps.

3. Manage suppressions properly

Make sure that any bounces, unsubscribes, spam complaints, and inactive users are being segmented and added to your suppression list.

4. Perform regular list cleaning

A valid email today could become a spam trap later on—there’s no way to avoid this! But you can minimize the impact by regularly verifying your list of recipients so you can remove invalid email addresses as they pop up.

You sent to a spam trap. Now what?

If you think you’ve sent to a spam trap, there are a few things you can do to prevent further damage and get your email deliverability back on track.

1. Temporarily stop sending non-triggered emails

If you’ve scheduled any bulk sendings, put them on pause until you clean your list. Only send essential emails that are triggered by users’ actions.

2. Check for blocklisting

Some Email Service Providers (ESPs) will monitor blocklists for you (MailerSend does this) and they’ll take the appropriate action to get delisted. But you can run a blocklist check and monitor for activity yourself with tools like MailerCheck. If you’ve been blocklisted, and you’re managing your own sending IP address, you’ll need to follow the steps laid out by the blocklist to get delisted. 

3. Segment recipients

Segment and exclude any recipients that appear to be inactive. For example: 

• Users that haven’t opened emails in the last 6 months

• Users with zero activity on your app since signup

• Users who haven’t logged in or used your services within the last 6 months

4. Verify your customers’ email addresses

Use an email verification service to check the validity of recipients’ email addresses and then exclude or remove any invalid or risky emails. MailerSend has a built-in email verification tool that makes it easy to clean your list and add invalid emails straight to your suppressions.

5. Check your signup forms and other points of collection

Double-check that your forms and email collection points are correctly validating emails when they’re being submitted.

How MailerSend helps with spam traps and deliverability

While we can’t stop a bot attack or prevent Google from repurposing inactive emails, we do have a few tools up our sleeve to help make it easier to catch spam traps and ensure good deliverability. 

• Built-in email verification tool: Upload a list of emails, whether 100 or 100,000, to verify in bulk. You can then export the list or sync it with your suppressions

• Email verification API: With the email verification API endpoint, you can verify a single email address or a list of emails. This allows you to send individual emails for verification when users signup to verify in real-time, or schedule bulk verifications

• Webhook events: Use email_single.verified and email_list.verified to trigger notifications or Slack updates about the status of your email verifications

• Automatic suppressions handling: Hard bounces, spam complaints and unsubscribes are automatically added to your suppressions lists, while emails that have soft bounced 5 times within 30 days are put on hold. You can also create blocklists with custom patterns, for example, to block specific domains

• Real-time activity: You can easily monitor deliverability with real-time activity for each and every email you send. Plus, you can use webhooks to set up notifications and catch issues early on

Don’t let spam traps derail your transactional email

Your transactional messages are a super important part of your user experience, and in many cases are crucial for the functionality of your app or service! Spam traps can and will find their way in if you let them, but with a few basic methods (that really should be part of your setup anyway), you can prevent them from getting into your customer lists and making an impact on your deliverability.