Spam Sign-Ups: How To Protect Your Domain Reputation

Vladislav Podolyako
Nov 30, 2021
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Sign-ups don’t come easy, so of course, you’re proud when you bring value to your audience and your email list grows. But there is a risk caused by spam sign-ups – bots providing fake email addresses to your sign-up forms and compromising your sender reputation. This article will tell you why fake sign-ups are dangerous and how to protect your business against them.

A little spoiler:

  • Add reCAPTCHA box to eliminate spambot sign-ups.
  • Block fake sign-ups with throttling.
  • Use double opt-in to verify email addresses.
  • Insert honeypot fields into sign-up forms.

What are spambots?

Spambots are computer programs built to find website sign-up forms and fill them in with illegitimate email addresses. These addresses can be completely fake or real but collected without the users’ knowledge. At first, a spam sign-up doesn’t seem to be an issue because you think that fake email addresses just won’t receive your messages. Unfortunately, the actual consequences can be much more dangerous. So why do incorrect sign-ups happen? Well, here are some of the reasons: 

  • Users make typos.
  • Subscribers use disposable (temporary) emails. 
  • Attackers want to get your email address and send you spam or phishing emails.
  • Someone wants to hurt your email deliverability and sender reputation.

How fake sign-ups hurt your email campaigns

Sign-up details impact your email outreach, domain reputation, and marketing efforts. Below are the biggest consequences of receiving fake information in new sign-ups

1. Your emails go into a spam folder. 

If you get an unwanted email from a service you’ve never subscribed to, especially sent to one of your corporate email addresses, you likely get angry and delete it. That’s how spam complaints happen. Unfortunately (but quite understandably) only a few would open it to hit Unsubscribe. And this is what happens if your email campaigns comprise multiple fake email addresses. Once your spam complaints increase, mail exchange providers can block your domain or IP address, and increasing hard bounce rates (% of undelivered emails) due to invalid email addresses will get you there even quicker. You’re probably far from getting on a blacklist, but we still recommend checking your deliverability with this email spam test.

2. Your key email campaigns’ metrics aren’t accurate. 

When your emails get spam complaints and are moved to the spam folder, your open rates (ORs) and click-through rates (CTRs) decrease. This can make you blame engagement issues like invaluable content, boring subject lines, poor targeting, or lack of personalization and spend hours trying to fix them when your real audience is actually happy with those parameters. That’s how your real customers’ interests get lost among spam contacts. However, don’t hurry to remove inactive users from your email list just yet as it’s likely that not all of them have fraudulent addresses. Instead, segment them into a separate list and try reengaging

3. Your website security can be breached.

Does that sound surprising? Well, don’t panic, but here’s how accepting fake email addresses results in cyberattacks. Criminals leave fraudulent addresses to get yours, and then they send you a phishing email. Hackers can compromise your customers’ sensitive data or payment details once you click on a malicious link or provide personal data. This is how your own website’s sign-up forms can be dangerous for your business. 

How to protect your email list from spam sign-ups

Now that we have explored the threats behind spambot sign-ups, it’s time to learn how to secure your email list from spam contacts

1. Use reCAPTCHA-enabled sign-up forms.

Users always appreciate one-step actions and often get annoyed when the sign-up process includes reCAPTCHA verification. But for business owners, the little “I’m not a robot” box is a decent defense against spambots. Asking the user to type a couple of words to prove they are a human gives you confidence in collecting actual email addresses.

2. Use the double opt-in method to filter fake subscriptions.

Two-factor identification is an additional step for new subscribers (similar to reCAPTCHA). Still, it’s an excellent way to make sure you attract people with a genuine interest in your topic and filter fake users. Since bots won’t follow the confirmation link from an email, you can be sure that your email list consists of legitimate recipients

3. Throttle numerous sign-up attempts.

Throttling is a configuration of your internet service provider (ISP) that limits the number of emails a user can accept within a specified time. Numerous subscription attempts look like fake sign-ups, so this is one of the most effective ways to stop suspicious email addresses from getting to your database. However, not all throttled emails are spam sign-ups, so to avoid your own marketing outreach attempts from being blocked, try this spam email checker before you hit Send. 

4. Include honeypot fields to remove spambot sign-ups.

Honeypot fields are additional tickable boxes on your subscription forms. These boxes aren’t visible to humans, but spambots automatically fill them in – and get trapped. This way, you can detect spam contacts and remove fake users from your email list immediately.   

How to identify suspicious email addresses 

When spambots submit fake information, they don’t act like humans, and you can detect their suspicious behavior (often only with special software). Here’s what should catch your attention:

  • Similar email domains — You can get several subscriber addresses that look alike (e.g.,,, etc.).
  • Simultaneous sign-ups for your other services — If you have several newsletters, bots can subscribe to them simultaneously, and these are always fake sign-ups.
  • Immediate sign-ups — Another sign of spambot email addresses is when programs immediately complete all fields of your subscription form –– humans require several seconds for this task. 
  • Registered private/corporate addresses — It looks strange when your company works in the B2B sector but your emails don’t look like corporate addresses or vice versa: when you expect personal addresses from subscribers’ email service providers like Hotmail or Gmail and get emails from other domains instead.
  • Unexpectedly high number of sign-ups — Multiple subscriptions within a short period indicate spambot sign-ups.
  • Blacklisted emails — If email addresses belong to blacklists, they are 100% fake sign-ups. You can check them online through both free and payable resources.
  • Email addresses with suspicious location data — Watch out for addresses with IPs registered in countries other than those stated by users, and pay attention to multiple sign-ups from one specific city or area. 
  • Addresses with random symbols — Often such emails, as well as those that don’t have anything in common with the first or last name of a user, are fake sign-ups or temporary addresses and should be checked.

How to remove spambot sign-ups 

If you’re 100% sure that an email is fake, you should delete this spam email from your list immediately. But don’t be in a hurry to do this with questionable addresses. Instead, isolate fake sign-ups in a suppression list and review them against several criteria like sign-up source, specific words, subscription date, etc. You probably use email software, so this exercise won’t be a tough nut to crack. 

We hope this article helps you grow a perfect domain reputation and a list of subscribers free from spam sign-ups!

Vladislav Podolyako
Vladislav Podolyako
Founder & CEO
Vlad’s decades of entrepreneurial wisdom and business building experience have allowed him to successfully mentor a diverse group of business owners, entrepreneurs in growing their companies. A recognized expert in the areas of transforming organizational culture and leadership development, B2B Sales, Marketing, spent more than 10 years building technology products, with a background in communication networks and electronic device engineering.

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