Summary
Sending emails to dead domains (invalid, non-existent, or inactive email addresses) severely damages email deliverability by harming the sender's reputation. This leads to high bounce rates, which are a critical signal for ISPs and email providers to identify potential spammers. As a result, these providers filter, block, throttle, or even blacklist the sender's emails. Sending to NX domains also signals flawed address collection and data hygiene practices. It is considered sending without permission, by definition spam. Furthermore, compromised lists due to 'bomb list' addresses further degrades reputation and deliverability. Maintaining clean lists through frequent validation and cleaning, using suppression lists, monitoring bounce rates, and obtaining valid permission are essential to mitigate these issues.
Key findings
- Reputation Damage: Sending to dead domains significantly damages sender reputation.
- High Bounce Rates: High bounce rates are a key indicator of poor list hygiene and can trigger spam filters.
- Filtering & Blocking: ISPs and email providers actively filter and block emails from senders with high bounce rates.
- NXDOMAIN Issues: Sending to NX domains points to fundamental flaws in data collection and hygiene processes.
- Permission Violation: Sending to invalid addresses is essentially sending spam without permission.
- Compromised Lists: Compromised lists due to list bombing further worsen deliverability metrics.
Key considerations
- List Validation: Regularly validate email addresses to identify and remove dead domains.
- List Cleaning: Implement a consistent list cleaning process to maintain a healthy sender reputation.
- Suppression Lists: Utilize suppression lists to avoid sending to known invalid addresses and those who have unsubscribed.
- Bounce Monitoring: Actively monitor bounce rates to detect and address deliverability issues promptly.
- Data Collection: Review and improve data collection and hygiene processes to prevent the accumulation of invalid addresses.
- Obtain Permission: Ensure that valid consent is obtained before sending emails to comply with anti-spam regulations.
What email marketers say
11 marketer opinions
Sending emails to dead domains (invalid or inactive email addresses) negatively impacts email deliverability by damaging sender reputation. This is because email providers monitor bounce rates, and high bounce rates signal poor list hygiene, potentially flagging the sender as a spammer. ISPs use bounce rates as a factor in determining sender quality, leading to throttling, blocking, or blacklisting. Regular list cleaning and validation are crucial to avoid deliverability issues.
Key opinions
- Damaged Reputation: Sending to dead domains hurts sender reputation, leading to deliverability issues.
- High Bounce Rates: Dead domains cause high bounce rates, which ISPs use to identify spammers.
- Poor List Hygiene: High bounce rates signal poor list hygiene to email providers.
- Filtering and Blocking: ISPs may filter or block messages from senders with high bounce rates.
- Blacklisting: Sending to dead domains can lead to blacklisting.
Key considerations
- Regular List Cleaning: Implement regular list cleaning practices to remove invalid email addresses.
- Email Validation: Validate email addresses before sending to minimize bounce rates.
- Monitor Bounce Rates: Monitor bounce rates to identify and address deliverability issues.
- Use Suppression Lists: Use suppression lists to avoid sending to known bad addresses.
- Handling of DNS: Ensure you are aware of NXDOMAINs and MX records for effective list hygiene and reputation management.
Marketer view
Marketer from Email Geeks explains that sending to an old "dead" domain that has been picked up by some reputation network is a bad idea, and if you are sending through someone else's infrastructure (e.g. AWS SES) then they might care if they see a lot of attempts to deliver to NXDOMAINs because it's a sign of a bad sender.
6 Feb 2024 - Email Geeks
Marketer view
Email marketer from Litmus answers that sending to non-existent or inactive email addresses (dead domains) damages your sender reputation over time. ISPs track these bounces and adjust your deliverability accordingly. Implement regular list cleaning and validation.
6 Sep 2024 - Litmus
What the experts say
3 expert opinions
Sending emails to dead or NX domains indicates fundamental flaws in address collection and data hygiene, and constitutes sending without permission, which is considered spam. Furthermore, sending to old 'bomb list' addresses, often resulting from malicious list bombing techniques, damages sender reputations, degrading deliverability and affecting future mailing success.
Key opinions
- Flawed Processes: Sending to NX domains indicates fundamentally flawed address collection and data hygiene processes.
- Lack of Permission: Sending to invalid addresses likely implies lack of permission, defining the email as spam.
- List Bombing Impact: Sending to 'bomb list' addresses degrades deliverability and damages sender reputations.
Key considerations
- Review Collection: Review and improve address collection and data hygiene processes.
- Obtain Permission: Ensure valid permission is obtained for all email addresses.
- Mitigate Bombing: Implement measures to mitigate the effects of list bombing and promptly remove affected addresses.
Expert view
Expert from Email Geeks shares that you should be concerned about sending to NX domains because it’s a sign that your address collection process or your data hygiene process is fundamentally flawed. And, more than domains that don’t deliver you really should be worried about how many folks are giving you addresses that DO deliver and now you’re spamming them.
21 May 2024 - Email Geeks
Expert view
Expert from Spam Resource explains that if you are sending email to addresses that are no longer valid it is likely you don't have permission, and the email is considered spam by definition.
9 May 2024 - Spam Resource
What the documentation says
5 technical articles
Sending emails to dead domains (invalid or non-existent addresses) results in high bounce rates, which negatively impacts sender reputation and deliverability. Major email providers like Google, Microsoft, SparkPost, and AWS SES monitor bounce rates and use them to assess sender quality. Excessive bounces can lead to emails being filtered as spam, accounts being suspended, and reputation penalties. Maintaining a clean email list, implementing suppression lists, and practicing regular list hygiene are crucial to avoid these issues.
Key findings
- Negative Signal: High bounce rates due to dead domains are a strong negative signal to email providers.
- Reputation Impact: High bounce rates degrade sender reputation.
- Spam Filtering: Excessive bounces can lead to emails being filtered as spam.
- Account Suspension: High bounce rates can result in account suspension by email service providers.
- SMTP Errors: Regular SMTP errors from dead domains indicate problems with sender practices.
Key considerations
- List Hygiene: Maintain a clean email list by removing invalid addresses.
- Suppression Lists: Implement suppression lists to avoid sending to known bad addresses.
- Bounce Handling: Utilize bounce handling features provided by email service providers to manage bounces effectively.
- Monitor Bounce Rates: Regularly monitor bounce rates to identify and address deliverability issues.
Technical article
Documentation from Microsoft's Smart Network Data Services (SNDS) shares that sending to dead domains results in a high number of undeliverable messages. Microsoft uses this data to identify potential spammers and filter their emails accordingly. Maintaining a clean email list is crucial for avoiding deliverability issues.
14 Dec 2024 - Microsoft
Technical article
Documentation from RFC 5321 describes that SMTP servers must provide accurate error responses for undeliverable emails. Regularly encountering such errors due to dead domains indicates a problem with the sender's practices and may lead to reputation penalties and deferred or blocked delivery.
2 Jun 2023 - RFC Editor
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