Why am I getting a lot of strange signups to my newsletter?
Michael Ko
Co-founder & CEO, Suped
Published 26 Apr 2025
Updated 16 Aug 2025
10 min read
Suddenly seeing an influx of strange signups to your newsletter list can be a perplexing and even alarming experience. One day, your subscriber growth is steady and organic, the next, you are inundated with registrations that just do not look right. This often involves peculiar email addresses, unusual capitalization, or signups originating from unexpected geographical locations. While it might seem like a harmless anomaly at first glance, these strange signups can signal deeper issues that impact your email program and overall deliverability.
These suspicious entries are usually the work of automated bots or malicious actors rather than genuine subscribers. Their presence can skew your analytics, inflate your subscriber count with unengaged or fake contacts, and ultimately degrade your sender reputation. A high volume of unengaged or invalid email addresses can lead to increased bounce rates, higher spam complaint rates, and even trigger email service providers (ESPs) to blocklist (or blacklist) your sending IP or domain.
Understanding why these strange signups occur and implementing robust preventative measures is crucial for maintaining a healthy email list and ensuring your legitimate messages reach the inbox. We will explore the common motives behind these unwanted subscriptions and outline effective strategies to protect your newsletter from bot attacks and fraudulent signups.
Understanding the nature of strange signups
Strange signups typically exhibit distinct patterns that differentiate them from genuine subscribers. Common indicators include unusual naming conventions, such as Firstname_Lastname12345 or random strings of characters, often combined with common free email domains like Hotmail or Gmail. These signups may also originate from suspicious IP addresses, often associated with VPNs or proxies, and they rarely engage with your content beyond the initial confirmation click. This kind of activity can be a strong indicator of a bot attack.
One primary reason for these bot-generated signups is subscription bombing. This tactic involves using a target's email address to sign up for numerous newsletters and services, overwhelming their inbox with a flood of legitimate but unwanted emails. The goal is often to distract the victim, making them miss crucial alerts, such as notifications of fraudulent financial transactions or account compromises. It creates a smokescreen for more nefarious activities happening elsewhere, as highlighted in a Hacker News discussion where a user reported being bombarded to hide an online order confirmation.
Another motive is email list validation. Spammers use signup forms to test lists of email addresses to see which ones are active. When your system sends a confirmation email (especially with double opt-in), it confirms the address is valid and active, making it more valuable for future spam campaigns or phishing attempts. This is a common way spammers verify email addresses before using them in larger attacks.
Additionally, some bots aim to conduct competitive intelligence or monitor content. They might subscribe to gain access to your content, promotions, or even observe your email sending patterns. While seemingly less harmful, it still introduces artificial engagement and can distort your metrics.
The impact of unwanted signups
Fake signups might seem like a minor nuisance, but their cumulative effect can significantly harm your email marketing efforts. The most immediate impact is on your data accuracy. Inflated subscriber counts give a false impression of your list's size and engagement, leading to skewed open rates, click-through rates, and conversion metrics. This makes it challenging to gauge the true performance of your campaigns and make informed decisions.
More critically, bot signups can severely damage your sender reputation. When you send emails to invalid or unengaged addresses, it increases your bounce rate, signaling to ESPs that your list quality is low. If these fake subscribers are used in subscription bombing attacks, the innocent recipients whose addresses were used might mark your emails as spam, further harming your email deliverability. Consistent low engagement or high complaint rates can lead to your emails landing in the spam folder or even your domain being placed on a blocklist (blacklist).
Beyond deliverability, there are financial implications. Many email service providers charge based on the number of subscribers on your list. If a significant portion of your list consists of fake or unengaged contacts, you are essentially paying to send emails to bots, wasting valuable marketing budget. This can also consume your sending quota faster than expected, potentially affecting your legitimate campaigns.
Maintaining a clean and engaged list is paramount for effective email marketing. Bot signups undermine the integrity of your data and can lead to long-term deliverability challenges, making it harder for your genuine messages to reach their intended audience. It is important to remember that even if you use double opt-in, malicious actors can still confirm subscriptions to achieve their aims.
Effective strategies to prevent unwanted signups
To combat strange signups and protect your newsletter, implementing several protective layers is essential. The single most effective strategy is to enable double opt-in. This requires subscribers to confirm their email address by clicking a link in a verification email sent to them. While it might slightly reduce your conversion rate compared to single opt-in, it significantly minimizes fake signups and ensures that only genuinely interested individuals are added to your list, improving your list quality and deliverability.
Another crucial defense is using CAPTCHA or reCAPTCHA on your signup forms. These tools are designed to distinguish between human users and automated bots, often requiring users to solve a simple puzzle or check a box. While they add a small step to the signup process, they are highly effective at blocking bot attacks. Implement invisible reCAPTCHA to minimize user friction.
Honeypot fields are also an excellent, user-friendly way to deter bots. These are hidden fields in your signup form that are invisible to human users but are detected and filled out by bots. If a hidden field is filled, your system knows it is a bot and rejects the submission without the user ever knowing. This adds an invisible layer of protection without impacting the user experience.
Employing email validation services at the point of signup can help. These services check if an email address is valid, deliverable, and not associated with known spam traps or disposable email providers. While some services come with a cost, they can save you money in the long run by preventing sends to non-existent addresses. For more advanced solutions, consider looking into tools that offer real-time bot prevention.
Best practice: implement a multi-layered defence
Relying on a single method to prevent spam signups is often insufficient. A robust defense against bots involves a combination of strategies, including double opt-in, CAPTCHA, and honeypot fields. Layering these methods increases your effectiveness significantly, making it much harder for automated scripts to infiltrate your subscriber list. Prioritize user experience while maximizing security measures.
Monitoring and maintenance for list hygiene
Even with preventative measures, ongoing vigilance is key. Regularly review your new signups for suspicious patterns, such as unusual email addresses, IP locations, or a sudden spike in registrations. Tools like Google Postmaster Tools can provide insights into your sender reputation and help you detect anomalies.
Regularly cleaning your email list is also crucial. Remove unconfirmed subscribers, bounced email addresses, and any contacts that show no engagement over a prolonged period. This process, often called list hygiene, improves your overall list quality, ensures better deliverability, and helps you avoid unnecessary costs from sending to dormant or invalid contacts. For more details on how to manage these issues, explore our guides on preventing bot signups and suspicious contacts on your email lists.
In addition to active monitoring, consider using specialized tools that track and analyze abnormal signup behavior. These tools can identify patterns indicative of bot activity, such as rapid signups from a single IP range, use of disposable email addresses, or unusual user-agent strings. Some services, like IPQualityScore, specialize in detecting and preventing fraudulent activity, including bot-driven signups, though they might not offer free APIs.
While blocking specific IP addresses or user-agent strings can provide temporary relief, remember that bots often rotate these identifiers. A more sustainable approach involves understanding the underlying motives of these attacks and implementing systemic solutions, such as those that leverage behavioral analysis or advanced bot detection algorithms. This ensures your defenses are adaptive and resilient against evolving threats.
Views from the trenches
Best practices
Always implement double opt-in for new newsletter signups to ensure subscriber authenticity and reduce bot registrations.
Regularly review your subscriber list for unusual patterns, suspicious email addresses, or sudden spikes in signups.
Utilize reCAPTCHA or honeypot fields on your signup forms to effectively deter automated bot attacks.
Leverage email validation services to verify addresses at the point of entry, ensuring deliverability and preventing bad data.
Common pitfalls
Relying solely on single opt-in, which leaves your list vulnerable to bot attacks and fake signups.
Ignoring strange signup patterns, allowing fraudulent entries to accumulate and skew your analytics.
Failing to regularly clean your email list, leading to increased costs and reduced deliverability.
Not implementing multiple layers of defense, making it easier for sophisticated bots to bypass single security measures.
Expert tips
Consider tracking the IP addresses of signups, even if for a limited time, to aid in troubleshooting and identifying bot origins.
Look for patterns in bot-generated email addresses, such as unusual numeric sequences or specific capitalization styles.
Explore advanced bot detection solutions that analyze user-agent strings and behavioral anomalies for more effective blocking.
Be aware that some attacks aim to confuse you by creating legitimate-looking email accounts that also receive spam, thus muddying detection efforts.
Expert view
Expert from Email Geeks says suspicious signups, especially from consistent IPs, could indicate a delivery monitoring tool rather than competitive intelligence.
2023-05-10 - Email Geeks
Marketer view
Marketer from Email Geeks says these signups might be used to give legitimacy to an account, making nefarious activity less noticeable.
2023-05-10 - Email Geeks
Protecting your newsletter
Strange newsletter signups are more than just a minor inconvenience, they pose real threats to your email program's health and effectiveness. From skewing your analytics and increasing costs to potentially damaging your sender reputation and leading to blocklisting, the repercussions can be significant. Understanding the various motives behind these bot attacks, whether it is subscription bombing, list validation, or competitive monitoring, is the first step toward effective mitigation.
Implementing a multi-layered defense strategy, including double opt-in, CAPTCHA, honeypot fields, and email validation services, is crucial. These measures act as strong deterrents, filtering out most automated threats. Beyond prevention, consistent monitoring and regular list hygiene are vital for maintaining a clean and engaged subscriber base. By proactively addressing these issues, you can protect your newsletter, ensure high deliverability, and focus on connecting with your genuine audience.
Hotmail or 
Gmail. These signups may also originate from suspicious IP addresses, often associated with VPNs or proxies, and they rarely engage with your content beyond the initial confirmation click. This kind of activity can be a strong indicator of a bot attack.
