What are the best ways to check for and prevent email typos on signup forms?
Matthew Whittaker
Co-founder & CTO, Suped
Published 19 Jun 2025
Updated 14 Aug 2025
8 min read
Summary
Preventing email typos on signup forms is crucial for maintaining a healthy email list and ensuring high deliverability rates. Incorrect email addresses lead to bounces, impact sender reputation, and waste marketing resources. While paid services offer comprehensive validation, there are effective strategies and basic checks you can implement without additional cost to help users self-correct and improve data quality at the point of entry.
Key findings
Client-side validation: Implementing real-time validation or typo correction suggestions on the form itself can significantly reduce input errors, such as @gnail.com instead of @gmail.com.
Server-side checks: Beyond basic syntax validation, performing checks like MX record lookups can verify if a domain exists and can receive mail, catching non-existent domains.
Confirmation emails: Double opt-in or confirmed opt-in remains one of the most reliable methods to ensure the user owns the email address and that it is valid, as the user must interact with a confirmation email to complete signup.
Suppression lists: Maintaining a custom suppression list of domains that have previously bounced helps prevent future sends to known bad or mistyped addresses.
Typo traps: Be aware that some typos might lead to typo spam traps, which are active email addresses set up by ISPs to catch senders who do not adequately validate their lists.
Key considerations
User experience: Balancing strict validation with a positive user experience is key. Overly aggressive validation can frustrate users.
Deliverability impact: Poor email quality due to typos directly affects your email deliverability, leading to messages landing in spam folders or being rejected.
Prevention vs. correction: While typo correction is helpful, focusing on prevention through clear form design and user guidance is often more effective.
Combining methods: The most robust approach involves a combination of client-side hints, server-side checks, and ultimately, confirmed opt-in. Nielsen Norman Group offers design guidelines for reporting errors in forms to improve the user experience.
What email marketers say
Email marketers often face the practical challenge of managing misspelled email addresses on their signup forms without incurring additional costs. Their approaches typically lean towards pragmatic, in-house solutions and leveraging features provided by their existing email marketing platforms. The goal is to catch common human errors before they negatively impact email campaigns and sender reputation, focusing on self-correction by the user where possible.
Key opinions
Custom suppression: Many marketers manually add bounced or known bad domains to a suppression file, preventing future sends to those addresses.
Leveraging ESP features: Some email service providers (ESPs) offer built-in features to block misspelled domains or provide spelling tips directly within their forms.
Pre-bounce checks: The ideal scenario is to prevent the bad address from being added at all, prompting the user to correct it themselves before submission.
Front-end validation: Implementing basic client-side validation can catch simple syntax errors and common typos like .con instead of .com.
Key considerations
Proactive prevention: While bounce suppression is good, proactive measures to prevent typos at the signup stage are more effective for list hygiene.
User self-correction: Designing forms that gently guide users to correct their own typos improves data quality and reduces friction.
Integration with existing systems: Consider how any typo-checking mechanism integrates with your current email marketing platform and database.
Scalability: For larger lists, manual suppression of individual bounced domains can become tedious, necessitating automated solutions for email validation.
Marketer view
Email marketer from Email Geeks notes that while they suppress bounced addresses, the focus should be on proactive measures. The ideal solution would enable users to self-correct typos before submission, preventing the bad address from ever entering the system.
20 Mar 2020 - Email Geeks
Marketer view
Email marketer from Centric Squared suggests that one of the simplest and most effective ways to reduce email input errors is to set expectations clearly on your confirmation page. Adding a strong call to action like 'Please check your inbox for a confirmation email' can encourage users to verify their input.
25 Jan 2023 - Centric Squared
What the experts say
Email deliverability experts offer more technical insights into combating email typos, particularly the insidious nature of typo trap domains. Their advice extends beyond simple syntax checks to DNS record validation and the strong recommendation for confirmed opt-in to mitigate risks to sender reputation and avoid landing on blacklists. They stress that even seemingly minor typos can lead to significant deliverability issues.
Key opinions
MX record validation: Performing a basic check for a valid MX record (or at least an A-record) can identify non-existent domains, catching common typos like gmail.con.
Typo trap concerns: One of the biggest concerns is typo trap domains, which may have valid MX records but are specifically set up to catch misaddressed emails and will not bounce.
Confirmed opt-in (DOI): Confirmed opt-in (Double Opt-In) is often recommended by blocklists as the primary method to ensure subscribers genuinely want to receive emails and have provided a correct address.
API validation: Some recipient validation APIs offer a 'did you mean' field, providing suggestions back to the customer, which can be integrated into signup forms.
Key considerations
Beyond basic checks: Simple syntax or MX record checks alone are insufficient to catch all types of typos, especially those that lead to active typo trap domains.
Preventing sends to traps: A robust solution should prevent sending to typo traps from the outset, as these will not generate bounces and can quietly damage sender reputation, potentially leading to your domain or IP being put on a blacklist.
Email authentication: While not directly preventing typos, strong email authentication (SPF, DKIM, DMARC) ensures that even if you send to a few bad addresses, your overall sending integrity is preserved.
Code libraries: Open-source libraries like Mailcheck can provide client-side typo suggestions, helping users correct common domain errors. This is a good starting point for in-house solutions, as described by David Gilbertson on Medium.
Expert view
Email expert from Email Geeks suggests that a very basic self-check can involve verifying if there's a valid MX record for the domain, or at least an A-record. This method helps catch obvious typos in the domain part, such as gmail.con.
20 Mar 2020 - Email Geeks
Expert view
Email expert from Word to the Wise explains that email list validation is crucial for managing sender reputation. Typos and invalid addresses increase bounce rates, which email service providers interpret as a sign of poor list management.
15 Mar 2023 - Word to the Wise
What the documentation says
Technical documentation and web development best practices strongly advocate for robust client-side and server-side validation to ensure data integrity on forms. This includes using appropriate HTML5 input types for email, implementing pattern matching for basic syntax, and providing immediate, helpful feedback to users. The emphasis is on proactive error prevention and user guidance, rather than relying solely on post-submission corrections.
Key findings
HTML5 validation: Using type="email" for email input fields enables basic browser-level validation and provides the correct keyboard for mobile users.
Real-time feedback: Providing immediate visual feedback as the user types helps them correct errors before attempting submission.
Confirmation fields: Some documentation suggests using a second 'confirm email' field to catch simple typing errors, though this can sometimes increase friction.
Client-side and server-side: A layered approach combining client-side (for user experience) and server-side (for security and reliability) validation is recommended for all form inputs, including email addresses.
Key considerations
Don't validate too early: Documentation often advises against showing error messages before a user has finished typing in a field, to avoid annoyance.
Clear error messages: Error messages should be clear, concise, and tell the user exactly what is wrong and how to fix it.
Accessibility: Validation should be accessible, meaning it works for users with assistive technologies and does not rely solely on visual cues.
Comprehensive validation: While syntax validation is a start, comprehensive validation also includes checking for common typos in domains (e.g., gnail.com) and preventing disposable email addresses (as discussed in related best practices).
Technical article
Documentation from web.dev advises that for optimal signup form best practices, developers should use the appropriate type attribute for email fields. This provides the correct keyboard on mobile devices and enables basic built-in browser validation, enhancing user experience.
18 Jul 2023 - web.dev
Technical article
Documentation from Nielsen Norman Group suggests a key design guideline for reporting errors in forms: avoid showing an error message until the user has completed input in a field and moved on. This prevents premature error notifications that can frustrate users.
