Summary
Accurately verifying your email list and identifying potentially harmful domains involves a combination of strategic list hygiene practices, cautious use of email validation services, and robust email authentication methods. Experts recommend regularly removing invalid addresses, unengaged subscribers, and potential spam traps. While email validation services can be helpful, their accuracy varies, necessitating careful evaluation and cross-referencing. It's crucial to 'verify customers' by monitoring signup patterns, list statistics, and delivery metrics, and to implement authentication protocols like SPF, DKIM, and DMARC for enhanced security and deliverability. Being aware of unusual signup patterns potentially indicating list bombing attacks is also vital.
Key findings
- List Hygiene: Regularly remove invalid addresses, unengaged subscribers, and spam traps to improve deliverability and sender reputation.
- Validation Service Caution: Approach email validation services with skepticism, test their accuracy, and cross-reference results between providers.
- Authentication Matters: Implement SPF, DKIM, and DMARC to authenticate emails and protect against spoofing, improving deliverability.
- Customer Verification: Focus on verifying the quality of customers, not just the validity of email addresses.
- List Bombing Awareness: Be vigilant for sudden increases in subscriptions that might indicate a list bombing attack.
- MX Record Importance: Properly configured MX records are essential for ensuring correct email routing and verifying sending domains.
- Suppression List Use: Utilize suppression lists to prevent sending emails to addresses that have bounced, unsubscribed, or reported spam.
Key considerations
- Real-Time Validation: Implement real-time email address validation at signup to prevent bad addresses from entering your list.
- Service Cost vs. Benefit: Carefully weigh the cost and benefits of using email validation services against manual cleaning and monitoring efforts.
- Content Engagement: Focus on creating engaging content to keep subscribers active and reduce the likelihood of spam complaints.
- Segmentation: Segment your email list based on engagement and target inactive subscribers with re-engagement campaigns.
- Pre-Send Deliverability Test: Verify deliverability, setup, and sender reputation before launching a mail flow, especially a new one.
What email marketers say
10 marketer opinions
Verifying your email list involves multiple strategies, from removing invalid addresses and unengaged users to implementing double opt-in processes. Email validation services can help identify spam traps and risky addresses, but should be used with caution and their results cross-referenced. Authentication methods (SPF, DKIM, DMARC) are also critical. Consistent list cleaning and real-time verification are recommended for maintaining a healthy email list and protecting your sender reputation.
Key opinions
- List Cleaning: Regularly remove invalid email addresses, unsubscribed users, and those who haven't engaged recently to improve deliverability.
- Email Validation Services: Use with caution, cross-reference results, and focus on identifying hard bounces and spam traps. They provide syntax checks, domain validation and risk assessments.
- Authentication: Implement SPF, DKIM, and DMARC to authenticate your emails and improve sender reputation.
- Real-Time Verification: Use real-time verification at signup to prevent invalid or harmful email addresses from entering your list.
- Email Validation Benefits: Email validation can improve deliverability, protect sender reputation and boost email marketing ROI.
- Spam Traps: Identifying and removing spam traps is essential to protect your sender reputation.
Key considerations
- Accuracy of Validation Services: Email validation services aren't always perfect, so test and compare different providers.
- Disposable/Role Accounts: Identify and handle disposable email addresses and role-based accounts (e.g., info@) appropriately.
- Content Quality: Consistently send valuable content to keep subscribers engaged and reduce the likelihood of being marked as spam.
- Engagement Segmentation: Segment your list by engagement and focus on re-engaging less active subscribers.
- Suppression Lists: Immediately suppress hard bounces and spam complaints to prevent future deliverability issues.
Marketer view
Email marketer from Neil Patel advises removing invalid email addresses, unsubscribed users, and those who haven't engaged recently. Also, segment your list and use double opt-in to improve quality from the start.
21 May 2022 - Neil Patel
Marketer view
Email marketer from ZeroBounce details the importance of identifying and removing spam traps from your email list. They share that hitting spam traps can severely damage your sender reputation, and suggest using an email validation service to detect and remove these addresses.
21 Mar 2023 - ZeroBounce
What the experts say
4 expert opinions
Verifying email lists and identifying harmful domains involves a multi-faceted approach. Some experts suggest caution regarding email validation services, highlighting potential scams and the importance of real-time sanity checks at signup. A key concept is to verify customers, not just domains, using gut feeling, list statistics, and delivery metrics for test sends. Additionally, unusual signup patterns could indicate a list bombing attack, requiring assistance. Before launching or troubleshooting mail flow, assess deliverability, setup, and reputation.
Key opinions
- Validation Service Skepticism: Many email validation services may be scams, particularly those with aggressive advertising.
- Customer Verification: Focus on verifying customers rather than just domains.
- Holistic Assessment: Use gut feeling, list statistics, and delivery metrics for test sends.
- List Bombing Awareness: Recognize unusual signup increases as potential list bombing attacks.
- Pre-Launch Assessment: Assess deliverability, setup, and reputation before launching a mail flow.
Key considerations
- Real-Time Sanity Checks: Implement real-time email address sanity checking at signup.
- Manual Review: Don't rely solely on automated tools; use human intuition.
- Monitoring Signup Patterns: Actively monitor signup patterns for suspicious activity.
- Seeking External Help: Be prepared to seek help if you suspect a list bombing attack.
- Reputation Management: Prioritize understanding and managing your sender reputation.
Expert view
Expert from Email Geeks states most email validation services are scams, especially those that advertise aggressively, but there is a need for real-time sanity checking at signup.
28 Mar 2022 - Email Geeks
Expert view
Expert from Email Geeks says 'You don't verify domains, you verify customers' and suggests starting with gut feel, then checking list statistics, and finally, delivery metrics for a test send.
10 Sep 2021 - Email Geeks
What the documentation says
5 technical articles
Accurately verifying email lists and identifying potentially harmful domains involves several technical standards and practices. The Domain Name System (DNS), particularly MX records, enables verification of email sending domains. Suppression lists are crucial for preventing emails from being sent to problematic addresses, protecting sender reputation. Email authentication methods like SPF, DKIM, and DMARC help verify the sender's identity and prevent email spoofing, increasing trust and deliverability.
Key findings
- DNS MX Records: MX records in DNS allow verification of mail exchangers for domains.
- Suppression Lists: Suppression lists are vital for excluding bounced, unsubscribed, and spam-reporting addresses.
- SPF Authentication: Sender Policy Framework (SPF) detects forged sender addresses by verifying authorized IP addresses.
- DKIM Authentication: DomainKeys Identified Mail (DKIM) verifies message authenticity through digital signatures.
- DMARC Authentication: DMARC builds on SPF and DKIM to enforce policies and provide reporting, protecting against email spoofing.
Key considerations
- Proper DNS Configuration: Ensure correct configuration of MX records to enable proper email routing and verification.
- Maintaining Suppression Lists: Keep suppression lists up-to-date to avoid sending to invalid or problematic addresses.
- Implementing SPF: Implement SPF to authorize sending IP addresses for your domain.
- Implementing DKIM: Implement DKIM to digitally sign outgoing emails.
- Implementing DMARC: Implement DMARC to define policies for handling emails that fail SPF and DKIM checks.
Technical article
Documentation from SparkPost explains suppression lists as critical for email deliverability by preventing emails from being sent to addresses that have bounced, unsubscribed, or marked emails as spam. This helps to protect sender reputation.
30 Jan 2025 - SparkPost
Technical article
Documentation from RFC-1035 specifies the protocol and formats required to use the Domain Name System (DNS) including the use of MX records to specify mail exchangers for domains, enabling verification of email sending domains.
23 Oct 2022 - RFC-1035
Are email list cleaning services useful for improving email deliverability, and how do they work?
Can 'invalid recipient' bounce messages be false positives and what should I do about it?
Do email list cleaning services effectively remove spam traps?
How can I identify and prevent suspicious or bot-generated email addresses in my lists?
How do email database cleaning services remove waste and invalid addresses?
How do I validate email addresses and maintain a clean email list?
How should I validate my email list hygiene and what factors should I consider when choosing a list cleaning service?
