How do bot signups impact email deliverability and what methods can prevent them?

Summary

Bot signups significantly degrade email deliverability by harming sender reputation through increased bounces, spam complaints, and reduced engagement. Preventative methods involve a layered approach: CAPTCHAs and honeypots on signup forms to identify and block automated submissions; double or confirmed opt-in to verify subscriber authenticity; email validation tools to remove invalid or risky addresses; monitoring signup sources for suspicious patterns; regular list cleaning to remove unengaged subscribers; IP warm-up for new IPs; and leveraging ESPs with built-in bot detection. Google reCAPTCHA analyzes user behavior, Cloudflare offers bot management tools, OWASP recommends rate limiting account creation, and Microsoft highlights the importance of sender reputation. The impact of bot signups depends on their ratio to genuine users, necessitating proactive and adaptive strategies.

Key findings

  • Negative Impact: Bot signups harm sender reputation, leading to deliverability issues.
  • Technical Solutions: CAPTCHAs and honeypots effectively block automated signups.
  • Verification Processes: Double/confirmed opt-in ensures genuine subscriber authenticity.
  • Address Validation: Email validation tools remove invalid/risky email addresses.
  • Source Monitoring: Monitoring signup sources detects suspicious bot activity.
  • List Hygiene: Regular list cleaning improves engagement and reputation.
  • IP Warming: Gradually warming up IPs establishes a positive reputation.
  • Behavioral Analysis: reCAPTCHA analyzes user behavior to identify bots.
  • Bot Management: Cloudflare's tools detect and mitigate bot activity.
  • Rate Limiting: OWASP recommends rate limiting account creation.

Key considerations

  • User Ratio: The impact of bot signups depends on their proportion relative to genuine users.
  • Layered Defense: Employ a multi-faceted approach combining different techniques.
  • Adaptive Strategies: Continuously adapt methods to counter evolving bot tactics.
  • ESPs: Leverage built-in ESP features for bot detection.
  • Balance: Balance security measures with a smooth user experience.

What email marketers say
15Marketer opinions

Bot signups significantly harm email deliverability by lowering sender reputation through increased bounce rates, spam complaints, and reduced engagement. Strategies to prevent bot signups include implementing CAPTCHA, using honeypots, employing double or confirmed opt-in processes, utilizing email validation tools, monitoring signup sources for suspicious activity, practicing regular list cleaning, and warming up new IPs gradually. Competent ESPs often provide built-in bot detection, and reCAPTCHA helps distinguish between human and bot interactions, while lead validation software assesses input validity. A multi-layered approach combining technical solutions and proactive list management is crucial.

Key opinions

  • Deliverability Impact: Bot signups directly lower sender reputation due to higher bounce rates and spam complaints.
  • Engagement Metrics: Reduced engagement from bot accounts negatively impacts deliverability.
  • Technical Prevention: CAPTCHA and honeypots are effective tools for identifying and blocking bots.
  • Opt-In Processes: Double or confirmed opt-in ensures only legitimate users are added to mailing lists.
  • Email Validation: Email validation tools remove invalid or risky email addresses before sending.
  • Source Monitoring: Monitoring signup sources identifies suspicious patterns indicating bot activity.
  • List Hygiene: Regular list cleaning improves engagement rates and prevents spam complaints.
  • ESP Capabilities: Competent ESPs offer built-in bot detection and rejection features.
  • IP Warm-up: Gradually warming up new IPs establishes a positive sending reputation.

Key considerations

  • Engagement Ratio: The impact of bot signups depends on their ratio to genuinely engaged users.
  • Multi-Layered Approach: A combination of technical solutions and proactive list management is essential.
  • Proactive Strategy: Continuous monitoring and adaptation are necessary to combat evolving bot tactics.
  • Relevancy: Ensure validation tools check whether the email is valid and the user intended to signup.
Marketer view

Email marketer from Campaign Monitor recommends gradually warming up new IPs by sending emails in increasing volumes to engaged subscribers. This helps establish a positive sending reputation with ISPs and improves deliverability.

January 2024 - Campaign Monitor
Marketer view

Marketer from Email Geeks shares that bot signups can have a huge impact on deliverability, depending on the ratio of bot accounts to genuinely engaged users. The impact might not be immediately apparent, and it could take time before the accumulation of illegitimate addresses is noticed.

November 2021 - Email Geeks
Marketer view

Email marketer from Litmus discusses the importance of regular list cleaning. Removing unengaged subscribers and bot signups improves engagement rates and prevents spam complaints, positively affecting deliverability.

June 2024 - Litmus
Marketer view

Email marketer from Email Marketing Forum suggests using honeypots, which are hidden form fields that only bots will fill out. If these fields are populated, the submission is flagged as a bot and rejected.

June 2024 - Email Marketing Forum
Marketer view

Marketer from Email Geeks explains that when a site is botted, you are sending to a mixture of addresses that bounce, accept mail but the recipient didn't actually sign up (resulting in spam reports or lack of engagement), and potentially spam traps.

October 2024 - Email Geeks
Marketer view

Email marketer from Mailjet recommends implementing CAPTCHA to prevent automated signups. CAPTCHA helps differentiate between human users and bots, blocking the latter from subscribing.

June 2021 - Mailjet
Marketer view

Email marketer from ZeroBounce shares using email validation tools to identify and remove invalid or risky email addresses before sending emails. This prevents sending emails to bot-generated addresses, improving deliverability.

March 2024 - ZeroBounce
Marketer view

Email marketer from Sendinblue shares that bot signups often result in spam complaints. These complaints directly damage your sender reputation, causing emails to land in the spam folder more often.

June 2024 - Sendinblue
Marketer view

Email marketer from HubSpot recommends monitoring signup sources to identify suspicious patterns, like sudden spikes in signups from unknown sources. This helps in detecting and addressing potential bot activity.

March 2024 - HubSpot
Marketer view

Email marketer from ActiveCampaign recommends using confirmed opt-in to avoid bot signups. By requiring subscribers to click a link in a confirmation email, it ensures that the email address is valid and owned by a real person.

December 2024 - ActiveCampaign
Marketer view

Email marketer from Neil Patel's Blog explains that bot signups lead to a lower sender reputation. A high bounce rate (due to fake email addresses) signals to ISPs that you're not maintaining a clean list, impacting deliverability.

January 2022 - Neil Patel's Blog
Marketer view

Email marketer from MailerLite advises segmenting email lists based on engagement. Sending targeted emails to engaged subscribers and separate campaigns to those who are less active can help maintain a healthy sender reputation and improve deliverability.

April 2024 - MailerLite
Marketer view

Marketer from Email Geeks shares if you’re using a competent ESP’s built in forms they should be doing bot detection and rejection for you automatically.

May 2021 - Email Geeks
Marketer view

Email marketer from Reddit user u/EmailGuru emphasizes the importance of double opt-in. This method requires users to confirm their subscription via email, ensuring that only legitimate users are added to the list, preventing bot signups effectively.

May 2021 - Reddit
Marketer view

Marketer from Email Geeks explains that reCAPTCHA determines if the input is coming from a human, while lead validation software checks whether the input value is valid or suspect. He continues to explain that both are useful as valid addresses can be entered maliciously, and invalid addresses can be entered accidentally.

October 2023 - Email Geeks

What the experts say
3Expert opinions

Bot signups negatively impact email deliverability by damaging sender reputation due to increased spam complaints and low engagement, signaling spamming practices to ISPs. Combining honeypots and CAPTCHAs on signup forms effectively identifies and blocks automated submissions. Implementing a double opt-in process verifies subscriber authenticity, ensuring only genuine users are added to the mailing list, further enhancing deliverability.

Key opinions

  • Sender Reputation: High bot signups damage sender reputation, leading to poor deliverability.
  • Honeypots and CAPTCHAs: These tools effectively identify and block automated submissions on signup forms.
  • Double Opt-In: Double opt-in verifies subscriber authenticity, reducing bot signups.

Key considerations

  • Combined Approach: Using a combination of techniques provides the most robust protection against bot signups.
  • Ongoing Monitoring: Continuously monitor signup activity to identify and mitigate emerging bot threats.
  • User Experience: Balance security measures with user experience to avoid deterring legitimate subscribers.
Expert view

Expert from Spam Resource responds by sharing that high rates of bot signups damage sender reputation because they lead to increased spam complaints and low engagement, which ISPs interpret as signs of spamming practices and subsequently hurt email deliverability.

September 2023 - Spam Resource
Expert view

Expert from Word to the Wise shares that implementing a double opt-in process can help verify the authenticity of new subscribers, ensuring only genuine users are added to the mailing list and improving deliverability rates by reducing bot signups.

January 2022 - Word to the Wise
Expert view

Expert from Word to the Wise explains that using a combination of honeypots (hidden form fields) and CAPTCHAs on signup forms helps to significantly reduce bot signups by identifying and blocking automated submissions.

April 2024 - Word to the Wise

What the documentation says
4Technical articles

Bot signups negatively impact email deliverability by harming sender reputation through increased bounces and spam complaints. To protect against this, documentation from Google reCAPTCHA, Cloudflare, OWASP, and Microsoft emphasizes the use of advanced techniques. reCAPTCHA analyzes user behavior to differentiate bots from humans, Cloudflare's bot management tools provide bot detection and mitigation, OWASP advises securing account creation with rate limiting, and Microsoft highlights maintaining a positive sender reputation to avoid deliverability issues.

Key findings

  • Behavior Analysis: reCAPTCHA analyzes user behavior to identify bots.
  • Bot Management Tools: Cloudflare's tools provide bot detection and mitigation techniques.
  • Account Security: OWASP advises securing account creation with rate limiting to prevent automated attacks.
  • Sender Reputation Importance: Microsoft emphasizes that maintaining a positive sender reputation is vital for deliverability.

Key considerations

  • Implementation Complexity: Advanced bot detection techniques may require technical expertise to implement effectively.
  • Resource Utilization: Bot management tools and analysis can consume system resources and require ongoing maintenance.
  • Adaptability: Bot detection methods must adapt to evolving bot tactics to remain effective.
  • Balance: Balance account security with a smooth user experience to avoid frustrating legitimate users.
Technical article

Documentation from Cloudflare shares Cloudflare's bot management tools provide advanced bot detection and mitigation techniques. This service can identify and block malicious bots attempting to sign up for email lists.

February 2024 - Cloudflare
Technical article

Documentation from Microsoft explains maintaining a positive sender reputation which is key for deliverability. Bot signups harm sender reputation due to bounces and spam complaints.

February 2025 - Microsoft
Technical article

Documentation from Google reCAPTCHA explains that reCAPTCHA analyzes user behavior to determine if a user is a bot. It uses advanced risk analysis techniques to protect websites from fraudulent activities such as spam and abuse.

November 2022 - Google reCAPTCHA Documentation
Technical article

Documentation from OWASP explains that account creation should be secured from automated bots to protect user data and system resources. They advise rate limiting to slow down bot attacks.

July 2023 - OWASP