What are the best ways to check for and prevent email typos on signup forms?

Summary

Preventing email typos on signup forms is a multifaceted endeavor, combining proactive validation, reactive cleaning, and user-friendly correction mechanisms. Key strategies encompass syntax checks, MX record verification, real-time validation tools (with caution regarding cost and false positives), typo suggestion, fuzzy matching algorithms, commercial validation services, double opt-in processes, bounce suppression, and A/B testing of signup forms. The effectiveness of certain validation services is debated, with some experts favoring clear form design and post-submission cleaning processes. A layered approach, blending technical validation with user experience considerations, appears optimal.

Key findings

  • Real-Time Validation: Real-time data validation tools can check email syntax, verify domain existence, and even ping mail servers to catch typos immediately.
  • Typo Correction Suggestions: JavaScript can automatically suggest corrections for common typos, enhancing user experience and reducing invalid signups.
  • Commercial Verification: Services like Kickbox and Neverbounce offer comprehensive email verification, identifying disposable addresses and other invalid formats.
  • Confirmed Opt-In (Double Opt-In): This method requires users to verify their email address, drastically reducing typo-related errors and ensuring valid user consent.
  • Bounce Suppression: Writing bounced domains to a suppression file prevents repeated sending to invalid addresses.
  • Fuzzy Matching: Algorithms like Levenshtein distance can suggest corrections based on character similarity to known-good domains.
  • Risk Analysis: Services like Google's reCAPTCHA Enterprise use risk analysis to detect suspicious patterns indicative of typos or fraudulent addresses.
  • MX Record Check: A basic check to ensure a valid MX record exists for the domain, can filter out some typos.
  • Blacklisting: Blacklisting misspelled domains prevents them from being added to your contact list.

Key considerations

  • Validation Service ROI: Carefully assess the cost-effectiveness of commercial email validation services compared to simpler validation techniques.
  • User Experience Balance: Strive for a balance between robust validation and a user-friendly signup process, avoiding overly aggressive validation that may deter valid users.
  • False Positives: Minimize false positives in validation rules to avoid blocking legitimate users with valid email addresses.
  • Continuous Improvement: Regularly test and update signup forms and validation methods to adapt to evolving typo patterns and validation best practices.
  • Post-Submission Cleaning: Do not solely rely on up-front validation; implement processes to clean your list periodically based on bounces and other activity metrics.
  • Form Design and Clarity: The importance of clear copy, labelling and design of forms.

What email marketers say
10Marketer opinions

Preventing email typos on signup forms involves a multi-faceted approach combining real-time validation, user feedback mechanisms, and backend verification processes. Strategies range from basic syntax checks and MX record verification to more sophisticated techniques like typo suggestion, fuzzy matching, and commercial validation services. Double opt-in remains a crucial step for confirming address validity. Regular A/B testing of signup forms and validation processes is also recommended for continuous improvement.

Key opinions

  • Real-time Validation: Implementing client-side validation using Regular Expressions (Regex) or real-time data validation tools provides immediate feedback, helping users correct errors before submission.
  • Typo Correction: Using JavaScript to automatically suggest corrections for common domain typos (e.g., @gnail.com -> @gmail.com) improves user experience and reduces invalid signups.
  • MX Record Verification: Checking for valid MX records can identify obviously invalid domains, though it doesn't catch all typos.
  • Double Opt-in: Employing a double opt-in process significantly reduces typo-related errors by requiring users to confirm their email address.
  • Commercial Services: Commercial validation services (e.g., Kickbox, Neverbounce) offer comprehensive checks for deliverability, disposable addresses, and other factors.
  • Fuzzy Matching: Fuzzy matching algorithms (like Levenshtein distance) can suggest corrections for typos by calculating the similarity between the entered domain and common valid domains.
  • Blacklisting: Blacklisting misspelled domains prevents them from being added to your contact list.

Key considerations

  • Validation Depth: Determine the appropriate level of validation based on risk tolerance and budget. A simple syntax check is better than nothing, but comprehensive validation catches more errors.
  • User Experience: Balance validation rigor with a smooth user experience. Aggressive validation can frustrate users if not implemented carefully.
  • False Positives: Avoid overly restrictive validation rules that could reject valid email addresses. Regularly review and adjust validation criteria.
  • Maintenance: Keep validation rules and typo suggestions updated to reflect current domain trends and common errors.
  • A/B Testing: Regularly A/B test different validation techniques and form layouts to identify the most effective approach for a specific audience.
Marketer view

Marketer from Email Geeks suggests a basic check for a valid MX-Record (or A-Record) to catch errors like "gmail.con", though it won't catch all typos.

January 2025 - Email Geeks
Marketer view

Email marketer from Stack Overflow advocates for fuzzy matching algorithms (like the Levenshtein distance) to suggest possible corrections. These algorithms compute the number of single-character edits required to change one word into the other and will suggest if its likely its a small typo.

June 2023 - Stack Overflow
Marketer view

Email marketer from Experian explains that using real-time data validation tools which can check the syntax of the email address, verify the domain exists, and even ping the mail server to ensure it's active can catch typos and invalid email addresses at the point of entry.

March 2022 - Experian
Marketer view

Email marketer from Quora recommends implementing client-side validation to provide immediate feedback to users about the format of their email address. Suggests integrating a 'did you mean' functionality to correct common domain typos.

July 2023 - Quora
Marketer view

Marketer from Email Geeks shares that they blacklist misspelled domains and implement spelling tips in forms to help users correct mistyped email addresses.

November 2022 - Email Geeks
Marketer view

Email marketer from Stack Overflow recommends using Regular Expressions (Regex) to validate email format on the client-side, allowing for instant feedback to the user if the entered email doesn't match the required pattern. Note: should not be solely relied upon as they do not guarentee that the email exists, only that it matches a specific pattern.

August 2023 - Stack Overflow
Marketer view

Email marketer from Reddit suggests using JavaScript to automatically suggest corrections for common email typos (e.g., "@gnail.com" becomes "@gmail.com") as the user types, improving the user experience and reducing invalid signups.

March 2024 - Reddit
Marketer view

Email marketer from Mailjet shares using double opt-in which requires users to confirm their email address by clicking a link in a confirmation email which significantly reduces the risk of typos and ensures the email address is valid and belongs to the user.

October 2021 - Mailjet
Marketer view

Email marketer from Medium recommends regularly testing your signup forms and email validation processes. Perform A/B testing with different validation methods and form layouts to discover what works best for your specific audience.

January 2024 - Medium
Marketer view

Email marketer from Marketing Over Coffee Forums recommends using a commercial service such as Kickbox or Neverbounce to verify the deliverability of email addresses, which can identify and prevent the use of typoed or disposable addresses. These services provide real time detection of invalid emails.

August 2021 - Marketing Over Coffee Forums

What the experts say
5Expert opinions

Preventing email typos on signup forms involves a mix of proactive validation and reactive cleaning. Experts suggest a blend of strategies including bounce suppression, real-time verification (with caution), and a strong emphasis on confirmed opt-in processes. While some validation services are viewed skeptically, the consensus leans towards multi-layered protection including server side and client side.

Key opinions

  • Bounce Suppression: Maintaining a bounce suppression list and checking against it before sending can prevent repeated attempts to deliver to invalid addresses, and warn users to correct before signup.
  • Confirmed Opt-In: Confirmed opt-in (double opt-in) is a highly effective method to ensure email address validity and user intent, dramatically reducing typos.
  • Real-time Verification: Real-time verification services can detect disposable email addresses and role-based addresses, improving list quality.
  • Form Design: Clear copy and design on forms, along with post-submission cleaning, is vital to the processes.

Key considerations

  • Validation Service Value: Carefully evaluate the ROI of email validation services, as some experts question their cost-effectiveness compared to other strategies.
  • Balanced Approach: Implement a balanced approach combining proactive validation (e.g., confirmed opt-in) and reactive cleaning (e.g., bounce suppression) for optimal results.
  • Post-Submission Cleaning: Don't neglect post-submission cleaning processes to remove invalid or inactive addresses from your list over time.
Expert view

Expert from SpamResource emphasizes the importance of using validation techniques that go beyond basic syntax checks. They recommend using real-time verification services that can detect disposable email addresses (DEA) and role-based addresses (like sales@) to improve list quality and sender reputation, thus reducing the risk of sending to mistyped or invalid addresses.

March 2023 - SpamResource
Expert view

Expert from Word to the Wise explains that although there are vendors that provide email validation and verification services, she thinks they're largely a waste of time. She suggests focusing on clear copy on forms, and post-submission cleaning.

January 2025 - Word to the Wise
Expert view

Expert from Email Geeks suggests checking your own bounce-suppression file for previously bounced domains and displaying a warning to users, allowing them to correct their input.

September 2021 - Email Geeks
Expert view

Expert from SpamResource recommends implementing a confirmed opt-in (double opt-in) process. This method requires subscribers to verify their email address by clicking on a link sent to the provided address, significantly reducing the number of typos and ensuring that only valid and interested users are added to the mailing list.

February 2025 - SpamResource
Expert view

Expert from Email Geeks shares that he writes bounced domains to a suppression file and checks future sends against it to avoid repeated sending to bad domains.

October 2022 - Email Geeks

What the documentation says
4Technical articles

The provided documentation highlights several technical approaches for checking and preventing email typos on signup forms. These methods range from basic syntax validation according to RFC specifications to leveraging specialized APIs and risk analysis features offered by Google Cloud and Mailgun. Microsoft also provides email validation methods using the System.Net.Mail.MailAddress class in .NET, which allows you to implement try and catch error prompts.

Key findings

  • Syntax Validation: RFC specifications define the formal syntax for email addresses, enabling developers to implement checks for basic correctness (e.g., @ symbol, valid characters).
  • Email Verification APIs: Mailgun's Email Verification API checks for typos, invalid domains, and disposable email addresses, providing a quality score for each address.
  • Risk Analysis: Google Cloud's reCAPTCHA Enterprise uses risk analysis to identify suspicious email patterns and prevent email fraud, including typos.
  • .NET Validation: Microsoft's System.Net.Mail.MailAddress class in .NET helps to validate email address formats and catch errors.

Key considerations

  • Comprehensive Validation: Implement a combination of syntax checks, API-based verification, and risk analysis for comprehensive typo prevention.
  • API Cost: Consider the cost and usage limits of email verification APIs when implementing these services.
  • False Positives: Monitor and adjust risk analysis settings to minimize false positives, which could block valid users.
  • Evolving Threats: Stay updated on new email fraud techniques and update validation methods accordingly.
Technical article

Documentation from Mailgun explains that their Email Verification API checks email addresses for typos, invalid domains, and disposable email addresses. It also provides a quality score indicating the likelihood of the email address being valid and safe to send to.

February 2022 - Mailgun
Technical article

Documentation from IETF specifies the formal syntax for email addresses, allowing developers to implement checks for basic structural correctness, such as the presence of an @ symbol, valid characters, and domain format.

March 2022 - Internet Engineering Task Force (IETF)
Technical article

Documentation from Google Cloud explains that using the reCAPTCHA Enterprise email fraud prevention feature can help detect and prevent email typos and disposable email addresses on signup forms. It uses risk analysis to identify suspicious email patterns.

August 2024 - Google Cloud
Technical article

Documentation from Microsoft details using the System.Net.Mail.MailAddress class in .NET to validate email address format, and try and catch errors. It can throw an exception if the format is invalid, which you can then handle and prompt the user to correct. Also states to not only rely on this.

July 2021 - Microsoft