How can I prevent bot signups on my email newsletter form?

Summary

Preventing bot signups on email newsletter forms requires a multi-faceted approach integrating various techniques. A layered strategy, beginning with edge proxies for bot scoring, progresses through detailed form validation on both client and server sides, implementation of double opt-in processes, and employment of honeypot fields to trap bots. CAPTCHAs, particularly the invisible reCAPTCHA and Cloudflare Turnstile, offer additional defense layers, while rate limiting submissions and utilizing email verification services help maintain list quality. CDNs with bot blocking capabilities and minimum form completion time requirements further deter automated signups. Real-time email validation APIs, custom human-verification questions, and specialized services like Email Hippo and Akismet enhance the defensive posture. A central theme is the ongoing need to adapt and refine these measures in response to evolving bot technologies and to prioritize user experience by avoiding overly intrusive security mechanisms.

Key findings

  • Multi-Layered Defense: Effective bot prevention relies on a combination of techniques at different stages of the signup process.
  • Confirmed Opt-In Effectiveness: Confirmed opt-in (double opt-in) significantly reduces bot signups by requiring email verification.
  • Client-Side and Server-Side Validation: Validating form input both on the client and server ensures data integrity and filters out many bots.
  • CAPTCHA and Challenge Systems: CAPTCHAs (including invisible versions) and other challenge systems deter automated submissions, but must be implemented carefully to avoid impacting user experience.
  • Honeypot Field Utility: Honeypot fields offer a simple and effective way to identify and block many bots.
  • Email Address Verification Importance: Email verification services help ensure that provided email addresses are valid and reduce the number of fake signups.
  • CDN Bot Blocking: Using a CDN with bot blocking capabilities adds a layer of protection at the network level.

Key considerations

  • Balancing Usability and Security: Striving for a balance between security measures and user experience is essential to avoid discouraging legitimate subscribers.
  • Bot Technology Evolution: Bot technologies continuously evolve, necessitating regular review and updates to bot prevention measures.
  • Potential for False Positives: It's important to monitor security measures to minimize false positives and avoid blocking legitimate users.
  • Implementation Complexity: Some bot prevention techniques require technical expertise for proper implementation and maintenance.
  • Cost Considerations: Some bot prevention services and APIs involve costs that need to be factored into the overall strategy.
  • Data Privacy: Implementing certain bot prevention methods may involve data privacy considerations that need to be addressed.

What email marketers say
14Marketer opinions

Preventing bot signups on email newsletter forms involves a multi-layered approach. Techniques include edge proxies for bot scoring, detailed form validation on both client and server sides, double opt-in processes, and honeypot fields to trap bots. Implementing CAPTCHAs, particularly the invisible reCAPTCHA and Cloudflare Turnstile, adds another layer of defense. Rate limiting submissions, using email verification services, CDNs with bot blocking, and setting minimum form completion times are also effective. Real-time email validation APIs, custom questions only humans can answer, and services like Email Hippo or Akismet further enhance protection. A key strategy is to adapt and combine various methods to address evolving bot techniques.

Key opinions

  • Multi-Layered Security: A combination of techniques offers the most robust defense against bot signups.
  • Client and Server Validation: Validating form data on both the client and server sides is crucial.
  • Double Opt-In: Confirmed opt-in processes effectively filter out bot-generated signups.
  • CAPTCHA Effectiveness: Using modern CAPTCHAs like Google's invisible reCAPTCHA and Cloudflare Turnstile can significantly reduce bot activity.
  • Honeypot Fields: Honeypot fields are simple yet effective in identifying and blocking bots.
  • Email Verification: Email verification services help ensure the validity of email addresses.

Key considerations

  • Usability vs. Security: Balancing security measures with user experience is important to avoid hindering legitimate signups.
  • Bot Evolution: Bot techniques are constantly evolving, requiring continuous adaptation of security measures.
  • CDN and Rate Limiting: CDNs and rate limiting can impact performance, so proper configuration is essential.
  • Privacy: Consider privacy implications of certain security measures.
  • False Positives: It's important to monitor for and minimize false positives to ensure legitimate users are not blocked.
Marketer view

Email marketer from Neil Patel explains rate limiting form submissions from a single IP address. This can help prevent bots from submitting multiple forms in a short period.

August 2021 - Neil Patel
Marketer view

Email marketer from Email Geeks shares that after switching on mandatory Turnstile checks, the Yahoo random email addresses stopped. The addresses also all ran the JavaScript timer on the page, each taking three seconds.

June 2021 - Email Geeks
Marketer view

Email marketer from Wordable shares implementing double opt-in. This ensures that only users who confirm their email address are added to your list, reducing the chance of bots.

September 2022 - Wordable
Marketer view

Email marketer from Patrick Coombe's Blog explains to use a "honeypot" field. This is a field hidden from users but easily detectable by bots. If the honeypot field is filled, it's likely a bot.

July 2024 - Patrick Coombe's Blog
Marketer view

Email marketer from Quora answers to use a content delivery network (CDN) which commonly have bot blocking abilities. They are able to check and challenge any requests for potential malicious intent.

August 2022 - Quora
Marketer view

Email marketer from Web Hosting Forum says to implement a minimum time that form can be completed in, if it is completed faster then it must be a bot.

June 2021 - Web Hosting Forum
Marketer view

Email marketer from G2 answers that they have used Email Hippo with their forms to prevent fake email addresses and bot sign ups.

August 2024 - G2
Marketer view

Email marketer from OptinMonster answers that to use a custom question on your email form with a question that bots can't answer, but a human can. This ensures they are human and helps prevent bot signups.

July 2021 - OptinMonster
Marketer view

Email marketer from Email Geeks shares useful steps in addition to or other than CAPTCHAs to handle the problem of bot signups including hidden fields that get auto-filled by bots and real-time email validation calls via API when the opt-in form gets filled out.

May 2021 - Email Geeks
Marketer view

Email marketer from Reddit mentions using email verification services to check if an email address is valid and active before adding it to your list. This can weed out bot-generated or disposable email addresses.

February 2022 - Reddit
Marketer view

Email marketer from Email Geeks shares experience of seeing similar spammy accounts from yahoo/Microsoft domains that bypassed captcha but were ranked as likely bots. They resolved to enhance captcha/form processing.

November 2023 - Email Geeks
Marketer view

Email marketer from Email Geeks shares a layered approach to forms and email address collection including using edge proxies, detailed form validation in HTML/JS and on the server side with API calls, and double opt-in.

December 2023 - Email Geeks
Marketer view

Email marketer from Email Geeks shares that they now fire off the Cloudflare Turnstile CAPTCHA when someone has typed more than three characters of their email address to avoid it executing on pageload.

September 2021 - Email Geeks
Marketer view

Email marketer from StackOverflow says to use Javascript to validate the email address on the browser before sending, and use server-side validation to validate once received to check that an email address meets the criteria.

March 2023 - StackOverflow

What the experts say
2Expert opinions

To prevent bot signups on email newsletter forms, experts at Word to the Wise recommend using confirmed opt-in, requiring subscribers to verify their email address, and implementing challenges like CAPTCHAs to ensure human verification.

Key opinions

  • Confirmed Opt-In is Key: Confirmed opt-in significantly reduces bot signups by requiring active verification.
  • Challenges Deter Bots: Implementing challenges such as CAPTCHAs can deter automated signups.

Key considerations

  • User Experience: Ensure that security measures, like CAPTCHAs, don't negatively impact the user experience for legitimate subscribers.
  • Adaptability: Bot technologies evolve, so security measures should be regularly reviewed and updated.
Expert view

Expert from Word to the Wise shares to implement challenges such as CAPTCHAs or other forms of human verification to deter automated signups.

December 2023 - Word to the Wise
Expert view

Expert from Word to the Wise explains that using confirmed opt-in is key. This requires the subscriber to actively confirm their address by clicking a link in an email, vastly reducing bot signups.

May 2024 - Word to the Wise

What the documentation says
4Technical articles

Technical documentation recommends leveraging risk analysis, behavioral analysis, and machine learning techniques, as offered by Google reCAPTCHA and Cloudflare Bot Fight Mode, to distinguish between humans and bots. Prevention strategies also include CAPTCHAs, account lockout policies, email verification, and integrating APIs like Akismet to identify and block spam submissions based on a comprehensive database.

Key findings

  • Advanced Risk Analysis: reCAPTCHA uses advanced risk analysis to differentiate between humans and bots effectively.
  • Behavioral Analysis and ML: Cloudflare Bot Fight Mode uses behavioral analysis and machine learning for bot detection and blocking.
  • OWASP Recommendations: OWASP suggests CAPTCHAs, account lockout, and email verification to prevent automated account creation.
  • Spam Database Integration: Akismet API leverages a vast spam database to identify and block spam submissions.

Key considerations

  • Implementation Complexity: Implementing some of these solutions, like Cloudflare Bot Fight Mode, may require technical expertise.
  • User Experience: CAPTCHAs can impact user experience; consider using invisible reCAPTCHA to minimize disruption.
  • API Costs: Services like Akismet may incur costs based on usage and subscription plans.
  • Ongoing Maintenance: Regularly review and update security measures to adapt to evolving bot tactics.
Technical article

Documentation from Cloudflare details that Bot Fight Mode uses various techniques, including behavioral analysis and machine learning, to identify and block malicious bot traffic. It can be configured to block, challenge, or log suspected bots.

December 2024 - Cloudflare
Technical article

Documentation from Google reCAPTCHA explains that reCAPTCHA uses advanced risk analysis techniques to distinguish between humans and bots. It offers different versions, including invisible reCAPTCHA, for a better user experience.

October 2024 - Google
Technical article

Documentation from Akismet answers that the Akismet API checks submissions against a constantly-growing database of user-submitted spam, so you can block the worst spam before it's even published.

September 2023 - Akismet
Technical article

Documentation from OWASP (Open Web Application Security Project) explains preventing automated account creation by using CAPTCHAs, account lockout policies, and email verification to reduce bot signups.

May 2023 - OWASP