What are the purposes of bots signing up for emails and accounts on websites?
Matthew Whittaker
Co-founder & CTO, Suped
Published 7 Aug 2025
Updated 16 Aug 2025
7 min read
I often get asked why bots sign up for email lists or create accounts on websites. It might seem like a random act of digital vandalism, but behind these automated sign-ups, there's usually a strategic, often malicious, purpose. These aren't just annoying glitches, they represent a significant threat to businesses and individuals alike.
The surge in bot-driven registrations can lead to serious consequences, from overwhelming your systems with junk data to compromising user accounts. Understanding these underlying motivations is the first step in effectively defending against them and protecting your digital infrastructure.
Whether it's for financial gain, data exploitation, or simply disruption, bad actors leverage automation to achieve their goals on a massive scale. Identifying their objectives helps us build more robust defenses and prevent issues like email deliverability problems.
The covert objectives of bot registrations
Bots signing up for emails and accounts are not aimless. Often, their primary objective is to execute specific types of cyberattacks or to facilitate broader fraudulent schemes. These automated programs are designed to interact with digital platforms, mimicking human behavior to blend in and carry out their nefarious tasks.
Bot activity
Primary purpose
Impact
List bombing
To overwhelm an email inbox and hide critical notifications, often preceding financial fraud or account takeover.
To identify weak points in website security, such as outdated plugins or default settings, for potential exploitation.
Data breaches, unauthorized access, system compromise.
Spam/fake reviews
To post unsolicited messages, misleading comments, or fraudulent ratings on public platforms.
Degraded user experience, damaged brand credibility, skewed analytics.
One significant purpose is to conduct a list bombing (or subscription bombing) attack. This involves signing up a single email address, often belonging to an unsuspecting victim, to hundreds or even thousands of mailing lists. The goal is to overwhelm the victim's inbox with legitimate emails from various services, effectively burying critical notifications like security alerts, password reset links, or transaction confirmations. This tactic is frequently used to mask fraudulent activities, such as unauthorized financial transactions, allowing attackers to exploit accounts before the victim can react. A ProPublica article highlights how this method is employed for harassment.
Another key reason for bot registrations is to harvest legitimate content. Bots may sign up for newsletters to collect promotional materials, exclusive offers, or proprietary content, which they can then repurpose for their own spam campaigns or analyze for competitive intelligence. This form of data harvesting can lead to intellectual property theft or the creation of more sophisticated phishing emails. They might also register accounts to gain access to gated content or services, which they can then exploit or resell.
The significant impact on your email program
When bots flood your email lists with fake or invalid addresses, it directly harms your email deliverability. Internet Service Providers (ISPs) and email providers like Google and Microsoft monitor sender reputation closely. A high bounce rate, a large number of inactive or invalid addresses, or an increase in spam complaints due to bot activity can severely damage your sender reputation, making it harder for your legitimate emails to reach the inbox.
Blocklisting: Your domain or IP may end up on a blocklist (or blacklist), preventing emails from reaching recipients.
Skewed analytics: Bot activity distorts key metrics like open and click rates, leading to inaccurate campaign assessments.
Impact on website security
Vulnerability probes: Bots test for weak points like outdated plugins or default login credentials.
Resource drain: Excessive bot traffic can overload servers, affecting site performance and user experience.
Spam content generation: Bots create fake accounts to post spam comments, reviews, or forum entries, damaging credibility.
Content scraping: Automated programs steal proprietary content, product data, or pricing information for competitor analysis or illicit use.
This degradation in sender reputation can lead to your emails being flagged as spam, redirected to junk folders, or even blocklisted (or blacklisted) by major providers. When your domain or IP address lands on a blocklist, it can take significant effort to delist it and restore your sending capabilities. The financial cost of sending emails to invalid addresses, coupled with the lost opportunities from legitimate messages not reaching their intended audience, can be substantial. You can learn more about this by checking out our guide to understanding blocklists.
Furthermore, bot sign-ups skew your analytics, making it difficult to gauge the true engagement and effectiveness of your email campaigns. Open rates, click-through rates, and conversion metrics become unreliable, leading to misguided marketing decisions. Cleaning these bot-generated email addresses from your lists is a continuous effort, consuming valuable resources and time that could be better spent on genuine audience engagement. This highlights the importance of understanding how to identify and prevent spambot sign-ups.
Bots aren't just targeting email lists, they also register accounts on websites to explore potential vulnerabilities. These automated programs might attempt to exploit insecure or outdated plugins, default settings, or weak passwords. If a bot successfully registers and receives a confirmation email or gains access to a profile, it can signal to the attacker that the system has weaknesses that could be further exploited for data breaches or unauthorized access. This is a common tactic, as described by AtData's blog on bot accounts.
Another widespread use of bots for website accounts is to engage in comment spam or to post fake reviews and ratings. On e-commerce sites or review platforms, bots can create numerous fake accounts to inflate or deflate product ratings, spread misinformation, or push malicious links through user-generated content. This not only degrades the user experience but can also harm a brand's credibility and search engine rankings.
Beyond direct attacks, bots might register accounts simply to scrape content from websites. This could involve gathering product data, pricing information, articles, or other proprietary content for competitive analysis, content theft, or to build their own deceptive websites. While less overtly malicious than a list bombing attack, content scraping can undermine the value of your original content and divert traffic from your site.
Protecting your digital assets
Combating bot sign-ups requires a multi-layered approach, focusing on proactive prevention and robust detection mechanisms. Implementing measures like CAPTCHAs, honeypot fields, and real-time email verification can significantly reduce the volume of bot registrations. These tools create hurdles that are difficult for automated scripts to overcome, while still allowing legitimate users to proceed easily. You can find more detail on how to prevent bot sign-ups.
Beyond these technical solutions, regular monitoring of your email lists and website activity is crucial. Identifying unusual patterns, such as a sudden surge in sign-ups from suspicious domains or geographical locations, can alert you to potential bot attacks. Promptly removing invalid or bot-generated contacts helps maintain a healthy email list and protects your sender reputation from unnecessary damage and potential blocklists (or blacklists). Google also provides advice on what to do if your email is being used for mass sign-ups.
Views from the trenches
Best practices
Always implement a multi-layered defense strategy for your forms, combining CAPTCHAs, honeypots, and IP reputation checks to deter bots effectively.
Regularly audit your email lists for suspicious entries and perform list cleaning to maintain high deliverability and prevent blocklisting.
Educate your team on the various types of bot attacks and their indicators to ensure quick identification and response.
Prioritize securing all web forms, not just newsletters, as bots target any entry point to find vulnerabilities.
Common pitfalls
Relying solely on CAPTCHAs, as sophisticated bots can often bypass them, making your forms still vulnerable.
Ignoring small spikes in sign-ups, which can be early indicators of a larger bot attack or list bombing attempt.
Failing to implement double opt-in, which leaves your lists open to invalid and bot-generated addresses, harming sender reputation.
Underestimating the impact of bot activity on analytics and business metrics, leading to skewed data and poor decision-making.
Expert tips
Monitor server logs for unusual traffic patterns or excessive requests from single IP addresses, as this can indicate bot activity.
Utilize web application firewalls (WAFs) to filter out malicious bot traffic before it reaches your forms and website.
Stay updated on the latest bot mitigation techniques and adjust your security measures accordingly to counter evolving threats.
Consider using behavior analysis tools that detect bot activity based on how users interact with your site, rather than just form submissions.
Expert view
Expert from Email Geeks says some research shows bot activities fall into several categories. One common type involves comment spam bots that automatically fill in forms. Another significant category is mailbombing services, which are often used to conceal fraudulent activities like wiping bank accounts by flooding the victim's inbox with legitimate emails. Additionally, some bots are simply designed to dump random addresses into forms, seemingly for harassment.
2021-10-06 - Email Geeks
Expert view
Expert from Email Geeks says the primary reason given to customers for securing their forms is to prevent mailbombing, especially to hide notifications about unauthorized connections or similar sensitive alerts. There's also a strong belief that some individuals engage in this behavior purely for malicious reasons.
2021-10-06 - Email Geeks
Why it matters for your deliverability
Understanding the various purposes of bots signing up for emails and accounts is vital for any organization operating online. These automated threats are far more sophisticated than mere annoyances, ranging from calculated fraud attempts like list bombing to systematic exploitation of website vulnerabilities and content theft. Each bot registration, whether for email or a website account, represents a potential vector for harm.
By recognizing the diverse motivations behind these activities, you can implement more effective defenses. Proactive security measures, continuous monitoring, and prompt response to suspicious activity are essential to protect your sender reputation, maintain data integrity, and ensure the overall security of your digital presence. Staying informed about evolving bot tactics allows for stronger, more resilient security strategies.
Google and 
Microsoft monitor sender reputation closely. A high bounce rate, a large number of inactive or invalid addresses, or an increase in spam complaints due to bot activity can severely damage your sender reputation, making it harder for your legitimate emails to reach the inbox.
