What is a generated email address?

A generated email address is often created by automated bots or scripts, typically for malicious purposes such as spamming, creating fake accounts, or exploiting web forms. These addresses often follow patterns (e.g., random characters, common words, or numerical sequences) and may use disposable email domains.

How do fake emails impact my sender reputation?

Sending emails to fake addresses leads to hard bounces, which indicate to ISPs that your list quality is low. High bounce rates negatively impact your sender reputation, making it more likely that your legitimate emails will land in spam folders or be blocked entirely, leading to poor email deliverability rates .

Can disposable email addresses be detected?

Yes, disposable email addresses can be detected using real-time email validation services that maintain databases of known temporary email domains. Integrating such services into your signup forms allows you to block these addresses at the point of entry.

What is the difference between a blocklist and a blacklist?

The terms blocklist and blacklist are often used interchangeably. They refer to a list of IP addresses or domains that have been identified as sources of spam or malicious activity. When an email sender's IP or domain is on a blocklist, emails from that sender may be rejected or sent to the spam folder by receiving email servers. Learn more about the difference between a blacklist and a blocklist .

Should I use double opt-in to prevent fake email addresses?

Yes, double opt-in is a highly effective method for preventing fake email addresses from entering your list. It requires subscribers to click a confirmation link sent to their email address, proving that the address is valid and they genuinely wish to subscribe.

How to identify and prevent fake or generated email addresses? - Sender reputation - Email deliverability - Knowledge base

Dealing with fake or algorithmically generated email addresses is a common challenge for anyone managing an email list. These deceptive entries can severely impact your sender reputation, inflate your marketing costs, and skew your engagement metrics. They often come from spam bots trying to exploit signup forms or gather data, and recognizing them can be tricky because they sometimes look legitimate at first glance.

The repercussions range from increased bounce rates, which signal poor list hygiene to internet service providers (ISPs), to landing on various blocklists (or blacklists). Being listed on a blocklist can significantly reduce your email deliverability, preventing your legitimate emails from reaching inboxes. Effective strategies for identifying and preventing these addresses are crucial for maintaining a healthy email ecosystem and ensuring your messages hit their intended targets.

This guide will walk you through the key indicators of fake and generated emails and outline robust prevention methods to safeguard your email lists and improve overall deliverability.

Identifying fake and generated email patterns

Fake email addresses often follow discernible patterns that, once understood, become easier to spot. One common characteristic is a generic or suspicious domain, especially those from free public email providers where the username is nonsensical or clearly generated, like noun.noun@gmail.com. Legitimate organizations typically send emails from addresses containing their company's official domain.

Red flags in email addresses

Nonsensical usernames: Look for random strings of characters, numerical sequences (e.g., johndoe12345@example.com), or patterns like test@test.com.
Disposable email domains: These are temporary email services meant for one-time use, like mailinator.com or tempmail.org. Many services publish lists of known disposable domains, and you can learn what are the best strategies to prevent disposable email signups.
Malformed syntax: Emails that don't conform to standard email address structure, such as missing an '@' symbol or a domain suffix, indicate a fake address.
Generic greetings and urgent language: While more related to phishing, such signs can suggest a broader pattern of suspicious activity or a generated message, as outlined by the Federal Trade Commission.

Analyzing the email domain is another critical step. Reputable businesses use their official domain names. If an email originates from a public domain like supportcompany@gmail.com rather than support@company.com, it's a strong indicator of a fake or spoofed address. Also, watch for subtle misspellings of legitimate domains (e.g., gooogle.com instead of google.com). You can also get more insight into how to identify and handle suspicious email addresses.

Behavioral analysis can also provide clues, especially concerning form submissions. A sudden influx of sign-ups within a short period, often with similar patterns in usernames or domains, points to bot activity. These are often indicators of a list bombing attack, which can also trigger spam trap activations and lead to blocklisting. Understanding how to identify email spam traps is key to maintaining a clean list.

Why fake emails are problematic

Fake or generated email addresses are more than just an annoyance, they pose significant risks to your email marketing efforts and overall business operations. The primary concern is their impact on your sender reputation. When you send emails to invalid addresses, they result in hard bounces. A high hard bounce rate signals to ISPs that your sending practices are poor, leading to lower inbox placement rates for your legitimate emails.

Problems caused by fake emails

Damaged sender reputation: High bounce rates and spam complaints lead to being flagged as a sender of unsolicited mail, affecting your domain reputation.
Increased marketing costs: Most Email Service Providers (ESPs) charge based on list size or emails sent. Sending to fake addresses means you're paying for non-existent engagement.
Skewed analytics: Metrics like open rates and click-through rates become unreliable, making it difficult to accurately assess campaign performance.

Impact on deliverability and security

Blocklisting (blacklisting): Repeatedly hitting invalid addresses can lead to your IP or domain being placed on an email blocklist, effectively blocking your emails from reaching major ISPs. More information can be found in our in-depth guide to email blocklists.
Increased spam complaints: If fake sign-ups are part of a broader attack, users might mark your emails as spam, further damaging your reputation.
Security vulnerabilities: Fake accounts can be used for malicious purposes, such as creating spam traps, phishing attempts, or fraudulent activities like affiliate fraud, as sometimes seen with Google accounts.

The long-term effects of ignoring fake email addresses can be devastating for your email program. It can lead to lower inbox placement, reduced campaign ROI, and a general erosion of trust with your audience. Preventing these issues at the source is far more effective than trying to clean up a contaminated list later. You might be interested in our article on email deliverability issues for a broader perspective.

Prevention strategies and tools

Proactive prevention is the most effective approach to combating fake and generated email addresses. Implementing robust validation mechanisms at the point of entry, such as signup forms or checkout pages, can significantly reduce the number of fraudulent entries on your lists. This ensures you only capture legitimate contacts, which is key to email list hygiene.

Effective prevention techniques

Real-time email validation: Integrate a real-time email validation API into your forms. These services check for syntax errors, domain validity, mailbox existence, and identify disposable email addresses. This is covered more comprehensively in strategies for email list validation.
CAPTCHAs and reCAPTCHAs: While sometimes a minor barrier for users, CAPTCHAs can deter automated bots from submitting fake data. Google's reCAPTCHA is a popular option.
Honeypot fields: These are hidden form fields that are invisible to human users but filled out by bots. If a honeypot field is filled, you know the submission is from a bot and can reject it, helping to prevent bot sign-ups.
Double opt-in: Requiring users to confirm their subscription via an email link verifies that the email address is valid and owned by the subscriber.

Implementing a combination of these methods creates a multi-layered defense. For example, using a real-time validation service combined with a honeypot can catch a significant percentage of fake signups without negatively impacting the user experience. You can also monitor your blocklist status to ensure your preventative measures are working.

Example: Basic honeypot field in HTMLHTML

<form action="/submit-form" method="POST">
    <label for="email">Email:</label>
    <input type="email" id="email" name="email" required>

    <!-- Honeypot field - visually hidden with CSS -->
    <div style="display:none;">
        <label for="website">Website:</label>
        <input type="text" id="website" name="website">
    </div>

    <button type="submit">Submit</button>
</form>

Beyond technical implementations, regular list hygiene is essential. Periodically reviewing your email lists for suspicious patterns, high bounce rates, or low engagement can help identify addresses that slipped through initial defenses. Removing inactive or invalid addresses regularly, preventing fake email registrations, and identifying spambot sign-ups are critical to maintaining good sender reputation. This proactive approach ensures your emails continue to reach the inbox, avoiding spam folders and blacklists.

Advanced detection and mitigation

For more sophisticated attacks, such as those involving AI-generated scam emails or complex botnets, more advanced detection and mitigation techniques may be necessary. These often involve analyzing a broader range of signals beyond just the email address itself.

One such technique involves reverse IP lookups and cross-referencing against known blocklists (or blacklists). If a series of sign-ups originates from an IP address with a poor reputation or known to be associated with spam activity, it's a strong indicator of fraudulent intent. Services that monitor various DNS-based blocklists (DNSBLs) can provide real-time alerts. You can also understand more about how DNSBLs affect deliverability.

Signal Category	Indicators of Fake/Generated Emails	Mitigation Strategy
IP address reputation	High volume of sign-ups from a single IP, IP listed on Spamhaus or Barracuda blocklists.	Implement IP reputation checks, block known bad IPs at the firewall level.
Behavioral anomalies	Unusually fast form completion, lack of mouse movements, repeated failed login attempts, unusual browser strings.	Utilize fraud detection software that analyzes user behavior, implement progressive profiling.
Email activity history	Email addresses associated with past spam complaints or non-existent recipients.	Cross-reference with internal suppression lists or known spam trap databases.
DNS records	Domains lacking valid MX records or SPF/DKIM authentication, as detailed by Crowdstrike in their guide on spoofed emails.	Perform DNS checks on domains, enforce email authentication protocols like DMARC, SPF, and DKIM.

Maintaining vigilance is key. Regularly auditing your sign-up sources and analyzing anomalies in your subscriber acquisition data can provide early warnings of malicious activity. By combining preventative measures with advanced detection, you can build a robust defense against fake and generated email addresses, protecting your email program's integrity and maximizing your deliverability.

Views from the trenches

Best practices

Implement multi-step verification to make it harder for bots to complete sign-ups.

Utilize reCAPTCHA or other CAPTCHA solutions on forms to deter automated entries.

Use honeypot fields in web forms to catch bot submissions without affecting user experience.

Regularly monitor your sign-up rates for sudden, unexplained spikes that could indicate bot activity.

Track the acquisition source of all new sign-ups to identify problematic channels.

Ensure your email authentication records (SPF, DKIM, DMARC) are correctly configured to prevent spoofing.

Common pitfalls

Over-engineering prevention methods, making sign-up processes too complex for legitimate users.

Ignoring early warning signs like increased bounce rates or suspicious email patterns.

Relying solely on simple email format checks that can be easily bypassed by sophisticated bots.

Not removing invalid or inactive email addresses, leading to continued deliverability issues.

Failing to track where fake sign-ups are originating, which prevents targeted mitigation.

Underestimating the impact of fake sign-ups on marketing costs and analytics accuracy.

Expert tips

Combine several prevention techniques for a layered defense against various types of fake emails.

Regularly update your email validation tools and blacklist (or blocklist) data to combat new bot tactics.

Segment your email lists based on engagement and remove unresponsive or questionable contacts.

Analyze email headers to identify discrepancies in sender information for suspicious emails.

For transactional emails, prioritize robust authentication to ensure legitimate delivery.

Consider a phased approach when implementing new prevention methods to minimize user impact.

Expert view

Expert from Email Geeks says that many of the simple rules for detecting fake emails can be easily bypassed. The best approach is to check against known bad actor blocklists using tools like reCAPTCHA, StopForumSpam, and DNSBLs to decide whether to accept or reject records.

2019-08-01 - Email Geeks

Marketer view

Marketer from Email Geeks says that these spam bots are typically designed to repeatedly exploit common out-of-the-box forms. If you make it fail, the bot will likely move on. It's important not to over-engineer solutions, but instead to monitor for increases in sign-ups or bounces and track the acquisition source.

2019-08-01 - Email Geeks

Protecting your email lists

The continuous battle against fake and generated email addresses requires a multi-faceted approach. It combines vigilant identification with robust, proactive prevention strategies. By understanding the common patterns of these addresses and the motivations behind their creation, you can significantly mitigate their impact on your email program.

Prioritizing email list hygiene not only protects your sender reputation but also ensures your marketing efforts are directed towards genuinely interested recipients. Investing in tools and practices for email address validation, alongside implementing layered defenses like CAPTCHAs and honeypots, will safeguard your lists and enhance overall deliverability. Remember, a clean list is the foundation of successful email marketing.