What are the reasons for seeing email addresses with a random number before the domain name, and how do I prevent them?

Summary

The appearance of email addresses with random numbers preceding the domain is a multifaceted issue arising from sloppy data collection, deliberate user actions, and automated bot activity. These addresses often indicate typo-squatting, attempts to evade spam traps, disposable email usage to protect privacy or bypass subscription requirements, or compromised data from paid traffic vendors. RFC 5322 allows numbers in the local part of the email, but the random format is unusual. To prevent this, experts recommend implementing real-time email validation, CAPTCHA, double opt-in procedures, AI-powered verification, robust data governance, transparency in signup processes, bounce rate monitoring, progressive profiling, avoiding purchased lists, stricter signup validation, secure authentication methods (SPF, DKIM, DMARC, TLS), and regular list cleaning.

Key findings

  • Data Collection Issues: Sloppy data collection methods, like scraping or bad database imports, can introduce these addresses.
  • User Intention: Users may intentionally use invalid addresses to protect privacy, avoid spam, or bypass subscription requirements.
  • Automated Bot Activity: Bots often generate random email formats for automated signups.
  • Typo-Squatting & Evasion: Random numbers may be a form of typo-squatting or an attempt to evade spam traps or bots.
  • Low-Value Signup Proposition: A high number of these addresses may indicate the signup offer is unappealing, leading to fake data.
  • Traffic Vendor Issues: Compromised data or poor traffic from paid vendors might be generating these addresses.
  • List Bombing: The email address might be part of a larger 'list bombing' attack.

Key considerations

  • Real-Time Email Validation: Implement real-time email validation to catch errors and invalid addresses at signup.
  • CAPTCHA Implementation: Utilize CAPTCHA to prevent automated bot signups with fake or invalid emails.
  • Double Opt-In: Employ a double opt-in process to confirm user intent and verify the email address.
  • AI-Powered Verification: Use AI-powered email verification tools to identify and filter suspicious addresses.
  • Data Governance Procedures: Establish and enforce robust data governance procedures for input validation and data quality.
  • Signup Transparency: Ensure transparency in the signup process to encourage accurate information.
  • Bounce Rate Monitoring: Monitor bounce rates and engagement metrics to identify and remove invalid addresses.
  • Progressive Profiling: Collect data gradually to reduce the incentive for users to enter fake information.
  • List Cleaning: Remove bad emails and non engaged emails with services. Do this regularly and monitor rates.
  • Vendor Due Diligence: Thoroughly vet and monitor traffic vendors to ensure the quality of their leads and data.
  • Security Protocols: Implement SPF, DKIM, and DMARC records for improved authentication and deliverability.

What email marketers say
13Marketer opinions

The presence of random numbers before the domain name in email addresses typically indicates invalid, fake, or disposable addresses. These addresses may stem from various sources, including sloppy data collection (scraping or database imports), bot signups, typo-squatting, or intentional attempts to avoid providing genuine contact information. Users may also use fake addresses to bypass subscription requirements, protect privacy, or avoid spam. Techniques to prevent the collection of these types of addresses include real-time email validation, CAPTCHA, double opt-in, AI-powered verification tools, robust data governance procedures, transparent signup processes, monitoring bounce rates, progressive profiling, and avoiding the purchase of email lists.

Key opinions

  • Source of Invalid Addresses: Random numbers in email addresses often point to typos, bot activity, fake accounts, or disposable emails.
  • Data Collection Issues: Sloppy data collection methods like scraping and database imports can introduce invalid email formats.
  • Intentional Avoidance: Users may intentionally use invalid addresses to bypass subscriptions, protect privacy, or avoid spam.
  • List Bombing: Someone maliciously signing up email addresses to lists to try and discredit the emails.

Key considerations

  • Real-Time Validation: Implement real-time email validation to catch errors and filter out invalid addresses during signup.
  • Double Opt-In: Use a double opt-in process to confirm the user's intention and verify the validity of the email address.
  • Data Governance: Enforce robust data governance procedures, including input validation and data quality standards.
  • Bot Prevention: Use CAPTCHA and other bot prevention techniques to minimize automated signups with invalid addresses.
  • List Cleaning: Regularly monitor bounce rates and engagement metrics to identify and remove invalid addresses from your email list.
  • Transparency at Signup: Be transparent during the signup process to encourage users to provide accurate information.
  • Progressive Profiling: Collect data gradually to reduce the temptation to enter fake information.
  • Avoid Purchased Lists: Do not use purchased email lists. Instead focus on organic sign ups.
Marketer view

Email marketer from Email Hippo Blog explains that users accidentally adding numbers may be a form of 'typo-squatting' when filling in web forms. Prevention includes real-time email validation to catch errors as they occur and user education by providing clear examples of correct email format.

September 2021 - Email Hippo Blog
Marketer view

Email marketer from Reddit explains it could be a simple typo, a bot creating fake accounts, or someone intentionally trying to avoid giving their real email. They advise implementing a confirmation email to ensure the user provided a valid address and genuinely wants to subscribe.

March 2022 - Reddit
Marketer view

Marketer from Email Geeks suggests that the strange email addresses are likely from sloppy scraping of addresses from websites or a bad database import from a spreadsheet. They also advise that if there are many such addresses, the whole list should be scrapped as no amount of cleaning will fix it.

July 2022 - Email Geeks
Marketer view

Email marketer from SendGrid suggests that monitoring bounce rates and engagement metrics, such as open and click-through rates, helps identify email addresses with suspicious patterns or invalid formats. High bounce rates indicate a significant presence of faulty or fake addresses, triggering list cleaning and improvement measures.

July 2022 - SendGrid
Marketer view

Email marketer from ZeroBounce Blog shares the random numbers may be an attempt to bypass subscription requirements without revealing a genuine email. Recommends using AI-powered email verification tools to identify and filter out suspicious email addresses during signup, and avoid purchasing email lists.

May 2022 - ZeroBounce Blog
Marketer view

Marketer from Email Geeks advises that If signup encourages bad data, then even double opt-in won't help, because confirmation emails will still be sent to bad addresses. It's important to be transparent during signup.

September 2021 - Email Geeks
Marketer view

Email marketer from LeadQuizzes suggests using progressive profiling to collect email addresses over time instead of all at once, as this reduces the temptation for users to enter fake information just to get immediate access. It also provides the opportunity to assess data quality over multiple interactions.

May 2021 - LeadQuizzes
Marketer view

Email marketer from StackExchange responds that one possible scenario is lazy/bot registrations with invalid emails to gain access to content/services without intending to engage further. Suggests utilizing email validation services or implementing logic that identifies patterns in email address data to filter out such entries.

June 2023 - StackExchange
Marketer view

Marketer from Email Geeks states the the emails are likely bots hitting subscribe forms, and that confirmed opt-in and better subscribe processing would eliminate those.

June 2024 - Email Geeks
Marketer view

Email marketer from Litmus reports that invalid email addresses are most likely from users who are attempting to keep their personal email addresses private or avoid potential spam. Suggests implementing a double-opt in process to verify valid emails and avoid invalid emails.

May 2021 - Litmus
Marketer view

Email marketer from MailerCheck Blog states that random number patterns in emails usually indicate disposable or fake addresses used to avoid providing real contact information. They suggest implementing CAPTCHA, double opt-in, and real-time email verification during signup to prevent these.

February 2024 - MailerCheck Blog
Marketer view

Email marketer from Medium explains that it may be someone participating in a list-bombing campaign, meaning that they've signed up a bunch of email addresses to lists to try and discredit the email addresses. Suggests using email validation services or implementing logic that identifies patterns in email address data to filter out such entries.

October 2022 - Medium
Marketer view

Email marketer from LinkedIn advises focusing on robust data governance procedures that enforce input validation and data quality standards, ensuring that only email addresses that meet predefined format criteria are accepted during registration. They advise focusing on the use of regular expression (regex) validation.

October 2021 - LinkedIn

What the experts say
6Expert opinions

Email addresses with random numbers before the domain often result from typo-squatting, attempts to evade spam traps, or a desire to hide personal information. Bot signups and low-value signup propositions can also contribute. Experts recommend stricter validation, CAPTCHA, email verification tools, double opt-in, robust data governance, and checking traffic vendors to mitigate these issues.

Key opinions

  • Typo-squatting/Evasion: Random numbers may be a form of typo-squatting or an attempt to evade spam traps and bots.
  • Privacy Concerns: Users may enter random numbers to hide personal addresses and avoid spam.
  • Bot Activity: Bots often use random email formats for automated signups.
  • Vendor Practices: Paid traffic vendors might be generating fake traffic with invalid emails.
  • Poor Value Proposition: A high number of these addresses may indicate the signup offer isn't resonating, leading users to provide fake data.
  • Spam Trap Creation: Spam traps are sometimes created by collecting fake email addresses and buying the associated domains.

Key considerations

  • Stricter Validation: Implement stricter validation at signup, checking for common typos and invalid formats.
  • Email Verification Tools: Use email verification tools to identify and filter out invalid email addresses.
  • Double Opt-In: Implement a double opt-in process to confirm the user's intention and verify the email address.
  • Robust Data Governance: Establish data governance procedures to ensure only valid formats are accepted.
  • Traffic Vendor Audits: Check traffic vendors to ensure they are not generating low-quality traffic with invalid emails.
  • Address Spam Traps: Actively avoid or mitigate the effects of spam traps.
  • Improve Signup Process: Focus on the signup process to reduce fake emails, and increase perceived value.
Expert view

Expert from Word to the Wise responds that one possible scenario is bot signups. They advise focusing on robust data governance procedures that enforce input validation and data quality standards, ensuring that only email addresses that meet predefined format criteria are accepted during registration.

October 2022 - Word to the Wise
Expert view

Expert from Spam Resource shares that users enter seemingly random numbers to hide their personal addresses and avoid spam. Using email verification tools or implementing a double-opt in process prevents these invalid emails.

August 2021 - Spam Resource
Expert view

Expert from Email Geeks shares that spam traps can be obvious and are sometimes created by looking at the fake addresses people put into lists and buying available domains.

July 2022 - Email Geeks
Expert view

Expert from Email Geeks explains that the users likely have an address similar to the fake one. He also suggests implementing code to stop trying to contact the domain after the first failure and points out that a high volume of such addresses suggests that the value proposition for providing an email address isn't resonating with people. Suggests mentioning a confirmation email during signup.

October 2023 - Email Geeks
Expert view

Expert from Spam Resource explains that addresses with seemingly random numbers could be a form of typo-squatting or an attempt to evade spam traps. Implementing stricter validation at signup, including checking for common typos and using CAPTCHA, can help.

May 2022 - Spam Resource
Expert view

Expert from Email Geeks suggests checking vendors who are paid to drive traffic to the site, as they might be paying people to fill in bad traffic and getting paid for that traffic.

May 2021 - Email Geeks

What the documentation says
4Technical articles

Technical documentation suggests that while the 'local-part' of an email address can technically include numbers, the random number pattern before the domain is generally indicative of invalid or manipulated addresses. To combat this, strategies include preventing automated bot signups using CAPTCHA, rate limiting, and honeypots; emphasizing user consent and double opt-in procedures to ensure valid emails; using feedback loops; and implementing modern authentication and security protocols (SPF, DKIM, DMARC, TLS) to improve email verification processes.

Key findings

  • Syntax Flexibility: RFC 5322 allows numbers in the local-part of an email address, but the random number before domain format isn't formally defined.
  • Bot Prevention Techniques: CAPTCHA, rate limiting, and honeypots deter bots from entering fake email addresses.
  • Consent and Opt-In: Double opt-in procedures ensure valid email addresses and user consent.
  • Security Protocols: Modern authentication (OAuth 2.0) and security protocols (SPF, DKIM, DMARC, TLS) improve email verification.

Key considerations

  • Implement Bot Protection: Use CAPTCHA, rate limiting, and honeypots to prevent automated signups.
  • Enforce Double Opt-In: Require users to confirm their email addresses via double opt-in.
  • Secure Email Infrastructure: Set up SPF, DKIM, and DMARC records to authenticate emails and improve deliverability.
  • Monitor Bounce Rates: Implement feedback loops to automatically remove bad email addresses.
Technical article

Documentation from RFC Editor explains the formal syntax for Internet email addresses. Although it doesn't address the specific case of random numbers, it describes the valid characters and structure allowed in the 'local-part' (before the @ symbol), which can technically include numbers, however the random number before domain is not formally defined.

February 2023 - RFC Editor
Technical article

Documentation from Microsoft shares that implementing modern authentication methods (like OAuth 2.0), setting up SPF, DKIM, and DMARC records, and using transport layer security (TLS) can improve email security and verification processes, thus preventing the collection of manipulated or fake email addresses.

September 2021 - Microsoft
Technical article

Documentation from Google explains the importance of obtaining consent before sending emails, suggesting that using double opt-in procedures can help ensure that email addresses are valid and that users genuinely want to receive communications, reducing the likelihood of encountering randomly generated or fake addresses. Also use feedback loops to automatically remove bad email addresses.

January 2025 - Google
Technical article

Documentation from OWASP shares techniques to prevent automated bot signups. Implementing CAPTCHA, rate limiting, and using honeypots can deter bots from entering fake or invalid email addresses, including those with random numbers. This strengthens email list quality and reduces the risk of spam.

December 2021 - OWASP