Understanding Email Bounce Rates, Spam Traps, and Deliverability Issues

Email marketing is the most influential business marketing channel for return on investment (ROI).

The best part? Any business can do it, whether you’re a small startup or a corporate enterprise.

Here’s the catch - you won’t get very far if you don’t know how to navigate high email bounce rates, spam traps, and other email deliverability issues.

But first - let’s get started with the basics.

What is email bounce rate?

Email bounce rate is the percentage of your rejected emails versus those that successfully reach the inbox.

An email bounce occurs whenever your email is rejected by the receiving mail server or internet service provider (ISP) due to a temporary or permanent issue. Examples of these errors include

• Using an invalid email address
• A typo or incorrect email syntax
• Spam prevention technology
• An issue with domain reputation or IP reputationⓘA score used by internet service providers to approximate the reliability and trustworthiness of an IP address.

Email bounce rate is arguably the most essential email marketing metric to monitor, as high bounce rates will tarnish your sender reputation.

The more email bounces occur, the more likely you will see more email bounces and additional email deliverability issues.

Let’s examine the two primary types to understand why email bounces happen.

How to reduce email bounce rate

Step 1 - Clean your email list

The most effective way to conquer email bounces is to clean your email list regularly.

Even if you’re confident that your email signups are all legitimate, emails decay surprisingly fast (22.71% every year!).

However, all you need to do to protect your email deliverability is to start using email validationⓘA process that determines if an email address uses valid syntax, exists on a given domain, and is configured to receive incoming email messages. An email validation tool is an email checker that identifies the status of each address.

For example, ZeroBounce’s email validation identifies over 30 email address statuses and sub-statuses with guaranteed 99% accuracy. Instead of just seeing a list of usernames and domains, you’ll know which emails are:

• Valid
• Invalid
• Spam traps
• Disposable emailsⓘA temporary email address that users can create using a temporary email website or creation tool. You can use a disposable email address for a brief period before it expires and becomes invalid.
• Abuse emails
• Catch-all emailsⓘAn email set up by a business to capture email messages sent to their name via an invalid address (e.g., j0hn@company.com instead of john@company.com). Catch-all inboxes receive a high volume of spam and may not be actively monitored by the owner.
• Toxic domains

Once you spot anything that’s not a valid email address, you can delete them from your list. From there, you can confidently send email campaigns to your list, knowing that each email will reach its destination.

Keep your email content lightweight

Email marketing best practices tell us to keep email content short and sweet.

While the text is lightweight, you must review the type of images used and file sizes. JPEG will offer the smallest size but also the lowest quality. PNG is a strong middle-ground that will allow you to maintain quality at the cost of a bigger file. Be sure to use them effectively.

Use double opt-in registration

With a standard email signup form, visitors can enter any email address they want, whether real or fake.

By requiring a double opt-in confirmation, you can send an automated email to the address to confirm that it’s valid. This tactic also effectively reduces spam complaints as users can verify that they want to receive your email content.

Use an email verification APIⓘAn API, or application programming interface, that allows an email verification tool to connect and communicate with another software application. during registration

In addition to manual email list cleaningⓘThe process of removing invalid and high-risk emails, such as spam traps or disposable emails, from an email list. Email list cleaning can be performed after gathering data via email validation., we strongly recommend adding an email verification API to your websites and landing pages.

Most email validation services provide their API for this purpose. This allows you to check every email visitors enter into your registration forms. If an invalid or risky email is detected, the email verifier blocks it.

Now that you know how to control your email bounce rate, let’s look at another significant threat to your email deliverability - spam traps.

What is a spam trap?

A spam trap is a fake email address created by email blacklist services and ISPs to catch users that don’t use email marketing best practices.

Emailing a spam trap is a telltale sign that a business does not clean its email lists. The email list likely contains addresses from purchased email lists or sources other than the owner's explicit consent.

There are three primary types of spam traps to know.

3 Types of spam traps

Pristine traps

A pristine spam trap, a honeypot, is an email address generated solely to target spammers. The address was never in use by a real person.

The last point is an important distinction, as it means there is no way to obtain this email address legitimately. There was no owner to sign up for your mailing list and show interest in your product.

Having pristine traps on your list means you’re obtaining emails, either bought or borrowed, that contain a planted spam trap.

Recycled traps

On the other hand, recycled traps (grey spam traps) are previously existing email addresses that once belonged to real people. ISPs can then repurpose those old, abandoned addresses as recycled traps.

Recycled traps can resemble any regular address: johndoe@gmail.com, janesmith22@hotmail.com, etc.

Despite once being an actual address, recycled traps are still a significant threat to your email deliverability.

Typo traps

A typo trap is a spam trap that intentionally includes typos and misspellings.

If you were to misenter an actual email address, i.e., support@yaahoo.com, it would bounce. However, a typo trap contains similar misspellings but will still read as “delivered.”

An ISP or blacklist provider intentionally created a “real” email address with the typo to catch those not using email marketing best practices.

Impact of spam traps

While a high email bounce rate is a more common threat (20.19% of emails are invalid), spam traps are deadly by design.

Though we found approximately 0.01% on lists last year, it only takes one to sabotage your email deliverability and sender reputation.

Here’s how spam traps can rapidly impact your domain reputation and email marketing ROI.

Your email domain and/or IP gets blacklisted

First and foremost, you can bet on your email domain and/or IP landing on one or more email blacklists/blocklists. Many spam traps come directly from those service providers, and many ISPs work with them to identify spammers.

Having your email domain blacklisted is a significant setback for your email marketing results. It negatively affects your engagement, delivery, and overall domain reputation.

After landing on a blacklist, your problems can begin to spiral further.

Increased email bounce rate

ISPs use blacklist services to identify untrustworthy senders. If your domain is on a blacklist, they’ll automatically block your email content resulting in more hard bounces.

It’s tough to resolve these types of hard bounces as the contacts on your list are still valid. The root of the problem is your negative sender reputation.

Until you can improve it, you’ll continue to bounce emails.

Tactics to avoid spam traps

Fortunately, blocking any spam trap from entering your email list is relatively simple.

Here are a few tactics your business should employ starting today.

Use email verification to check for traps

Email list cleaning isn’t just for reducing bounces; it can identify spam traps and other high-risk email addresses.

Be aware, however, that not all email verification tools can identify spam traps. Research the company you choose for your email cleaning to determine if they can accurately identify pristine, typo, and recycled traps.

ZeroBounce can identify all types of spam traps. You can use our email verification services by uploading your email list manually, and we’ll purge any spam traps from your database.

Alternatively, set up the ZeroBounce API on your email registration and signup forms to automatically block spam traps from entering your email list.

Never buy or borrow email lists

We can never recommend buying or borrowing new email leads from anyone.

While some services may guarantee a list that’s never been sold or shared, the risk is too significant to ignore. All it takes is one planted spam trap to have rippling consequences on your domain reputation.

No matter where you obtain your email addresses from, always circle back to step number one - email verification.

Once again - double opt-in registration

Best email marketing practices always include double opt-in signups.

This tactic is effective against spam traps, as many are bot-generated. There won’t be a party on the other end to respond to the confirmation email, which stops the spam trap from making it to your list.

However, it’s worth noting that it is possible to program a bot to respond to confirmation emails. Using these additional best email marketing practices is never an excuse to avoid cleaning your list.

Monitor your domain and IP reputation

Finally, any business serious about its email marketing should actively monitor both domain reputation and IP reputation.

Many online services, including ZeroBounce, actively monitor unusual and unwanted activity. If you end up on an email blacklist, you’ll receive immediate notification and a description of what went wrong. This allows you to take action and remedy the problem before it can impact your emails.