Summary
Email validation at the code level involves a multifaceted approach, with the consensus being that no single method is foolproof. Confirmed opt-in consistently emerges as the most reliable technique. Basic validation often starts with regular expressions to check syntax, though this method has limitations. More advanced techniques include DNS lookups for MX records, and employing dedicated libraries (e.g., Python's email-validator). External validation services offer comprehensive checks, but they can be costly. Considerations also include managing budget constraints, the potential for losing valid addresses, avoiding unreliable SMTP validation, preventing email injection vulnerabilities, and maintaining overall email list hygiene.
Key findings
- Confirmed Opt-In: Confirmed opt-in is the most effective email validation method.
- Regex Inadequacy: Regular expressions alone are insufficient for complete email validation.
- Third-Party Benefit: Third-party validation services offer comprehensive checks but cost money.
- Importance of DNS: DNS lookups for MX records can verify domain existence.
- Library Benefit: Libraries provide validation through domain name validation, address parsing and DNS queries.
- All methods are imperfect: Remember that all email validation methods are imperfect.
Key considerations
- Budget Constraints: Budget constraints limit use of paid validation.
- Avoid Data Loss: Aggressive validation may lose valid addresses.
- SMTP Unreliability: SMTP validation should be avoided as it is unreliable.
- Security Required: Security should be prioritised to prevent injection vulnerabilites
- Email Hygiene: Email hygiene is important for deliverability
What email marketers say
16 marketer opinions
Validating email addresses at the code level involves various methods, ranging from simple syntax checks using regular expressions to more complex techniques like DNS lookups and third-party validation services. Confirmed opt-in is consistently recommended as the most reliable approach. Other suggestions include reconfirmation campaigns, identifying patterns in suspicious emails, and leveraging email performance data to weed out inactive addresses. External validation services offer comprehensive checks but come at a cost. It's also crucial to consider factors like budget constraints and potential data loss when choosing a validation method.
Key opinions
- Confirmed Opt-In: Confirmed opt-in remains the gold standard for ensuring valid email addresses.
- Regular Expressions: Regular expressions can catch basic syntax errors, but are insufficient for complete validation.
- Third-Party Services: Third-party validation services offer comprehensive checks but may be costly.
- DNS Lookups: DNS lookups for MX records can verify the existence of the email domain.
- Email Performance: Email performance metrics (e.g., opens, clicks) can indicate whether an address is active and valid.
- Bulk Validation: Bulk email validation can provide specific info on errors and deliverability.
Key considerations
- Budget: Budget constraints may limit the use of paid validation services.
- Data Loss: Aggressive validation methods may result in the loss of valid email addresses.
- SMTP Validation Limitations: Avoid SMTP validation due to rate limits and greylisting causing it to be unreliable.
- Regex Limitations: Regex is limited as the sole validator
Marketer view
Marketer from Email Geeks mentions you could also pay a third-party validation service, whilst it will catch a lot of typos, they are no substitution for confirming the address when you get it.
23 Jun 2024 - Email Geeks
Marketer view
Marketer from Email Geeks shares that if you're on a budget and really don't mind loosing some valid addresses, you could remove any address with numbers or more than one full stop/period.
7 Apr 2023 - Email Geeks
What the experts say
2 expert opinions
Email validation is crucial for maintaining good email hygiene and deliverability, but all validation methods are imperfect. Confirmed opt-in is the most reliable approach. For high bounce rates, consider using a list cleaning service. Methods like syntax checking, domain verification, and SMTP handshakes can be used, but their limitations should be acknowledged.
Key opinions
- Imperfect Validators: All email validation methods have limitations.
- Confirmed Opt-in: Confirmed opt-in is the most reliable validation method.
- List Cleaning Services: List cleaning services are beneficial for high bounce rates.
Key considerations
- Method Limitations: Acknowledge the limitations of syntax checking, domain verification, and SMTP handshakes.
- Email Hygiene: Good email hygiene is essential for deliverability.
Expert view
Expert from Word to the Wise explains maintaining good email hygiene by removing invalid email addresses from your contact list is essential for deliverability. Suggests methods like syntax checking, domain verification, and SMTP handshakes, but notes these are imperfect and confirmed opt-in is superior.
25 Jul 2021 - Word to the Wise
Expert view
Expert from Spam Resource responds with the reminder that all email validators are imperfect. Sending a confirmation email and requesting the recipient to click on a link is the most reliable way to validate an email address. If bounces are high, use a list cleaning service that performs mailbox validation.
30 Oct 2023 - Spam Resource
What the documentation says
5 technical articles
Email validation at the code level involves various techniques as detailed in technical documentation. Regular expressions are commonly used to check the syntax, ensuring a valid prefix, @ symbol, and domain. Input validation, especially using allow lists and escaping special characters, is crucial for preventing email injection attacks. Understanding the formal email address syntax defined in RFC 5322 is essential. Libraries like the email-validator in Python offer comprehensive validation by incorporating domain name validation, address parsing, and DNS queries. Different languages, like Javascript, also have validation techniques available including regex.
Key findings
- Regex Validation: Regular expressions are used for basic email syntax validation.
- Input Validation: Proper input validation prevents email injection attacks.
- RFC 5322: RFC 5322 defines the formal syntax for email addresses.
- Library Validation: Libraries such as email-validator in Python provide comprehensive validation.
- Language Validation: Different languages have validation methods like using Regex in javascript
Key considerations
- Regex Limitations: Regex-based validation has limitations and requires additional checks.
- Security: Email validation must prioritize security to prevent injection vulnerabilities.
Technical article
Documentation from RFC Editor outlines the formal syntax for email addresses. It details the allowed characters, structure of the local part and domain, and the use of comments and folding whitespace. It's important for understanding the technical specifications behind email address validation.
30 Mar 2024 - RFC Editor
Technical article
Documentation from Python Docs answers a question about Email Address Verification by introducing the email-validator library, which incorporates domain name validation, address parsing, and DNS queries to confirm the structure and legitimacy of an email address.
23 Oct 2021 - Python Docs
How can I accurately verify my email list and identify potentially harmful domains?
How can I identify and prevent spam/bot traffic at email subscription points?
How can I prevent bot signups on my email newsletter form?
How can I use an API to suppress or reject fake emails on my signup form?
How do I validate email addresses and maintain a clean email list?
How do I validate the structure of an email account and what are some valid email address examples?
