What are the best practices for mailing duplicate opt-ins and how do they affect deliverability?

Summary

Mailing duplicate opt-ins significantly impacts email deliverability. Experts and marketers agree that sending unwanted or duplicate emails annoys recipients, leads to spam reports, unsubscribes, and harms sender reputation. This results in ISPs deprioritizing emails, potentially directing them to spam or promotional folders, and may cause the loss of engaged subscribers. Addressing data management issues, preventing list bombing, implementing sunset policies, and distinguishing between giveaway entries and genuine subscriptions are crucial. Furthermore, preference centers, segmentation, personalization, regular list cleaning, and deduplication tools are vital for maintaining list hygiene and deliverability. Automated systems can provide tailored experiences for resubscribers. Maintaining low spam rates and adhering to email standards demonstrate respect for recipients and ensure positive sender reputation.

Key findings

  • Negative Recipient Experience: Duplicate emails annoy recipients, leading to increased spam reports and unsubscribes.
  • ISP Deprioritization: ISPs identify and filter similar emails, potentially directing them to spam folders.
  • Data Management Problems: Recurring sign-ups with identical emails can reveal data management issues.
  • Loss of Subscribers: High unsubscribe rates stemming from repetitive emails result in the loss of valuable subscribers.
  • Need for Email List Hygiene: Regularly maintain the health of the email list.
  • Harmful to Sender Reputation: Sender reputation is crucial for whether emails are marked as spam.
  • Importance of Low Spam Rates: Adhering to a low spam rate is essential.
  • List Bombing Problems: Subscribing users to many lists without consent will lead to sender reputation problems.
  • Ineffective Sending Strategies: Sending the same message to unengaged users will hurt deliverability.

Key considerations

  • Obtain Consent: Ensure that the receivers want multiple messages.
  • Monitor Feedback: Keep track of the complaint rate.
  • List Maintenance: Ensure the list is regularly maintained.
  • Comply with Regulations: Maintain compliance with email regulations.
  • Prioritise Recipient Preferences: Always show that the receiver is valued.
  • Consider Data Security: Ensure there are no data leaks, vulnerabilities or threats.

What email marketers say
9Marketer opinions

Mailing duplicate opt-ins can negatively impact deliverability. Best practices involve understanding why users are re-subscribing, implementing preference centers, segmenting lists, personalizing content, regularly cleaning email lists, and using deduplication tools. Automation can provide different email flows for re-subscribers, and sunset policies help remove inactive users, maintaining a healthy sender reputation.

Key opinions

  • Understanding Re-subscriptions: Investigate the reasons behind frequent re-subscriptions to address underlying issues.
  • Preference Centers: Implement preference centers to allow users to control mail frequency and content types.
  • Segmentation & Personalization: Segment lists and personalize content to increase engagement and reduce unsubscribes.
  • List Cleaning: Regularly clean email lists by removing inactive or duplicate subscribers.
  • Deduplication Tools: Utilize deduplication tools to prevent sending multiple emails to the same person.
  • Automation for Re-subscribers: Use automation to provide different email flows for users who re-subscribe within a short period.
  • Sunset Policies: Implement sunset policies to remove inactive subscribers and maintain list hygiene.

Key considerations

  • Complaint Feedback Loops: Consider if subscribers use domains that provide complaint feedback loops to monitor spam reports.
  • List Hygiene Impact: Recognize that multiple entries for one subscriber can indicate issues with list hygiene and data management.
  • Sender Reputation: Maintain a healthy sender reputation by preventing subscribers from receiving the same emails repeatedly.
  • Welcome Series Adjustment: Adjust welcome series for re-subscribers, acknowledging their repeated interest without overwhelming them.
  • Engagment: Monitor key metrics such as open rates and click rates to determine the health of the email list and adjust any sending strategies.
Marketer view

Email marketer from Neil Patel Digital explains that sending too many emails to the same subscriber can lead to decreased engagement and increased unsubscribe rates. Segmenting lists and personalizing content can help.

June 2021 - Neil Patel Digital
Marketer view

Email marketer from Email Geeks suggests exploring why users are signing up repeatedly and whether they are using domains that provide complaint feedback loops before deciding how to manage the situation.

August 2024 - Email Geeks

What the experts say
8Expert opinions

Mailing duplicate opt-ins can severely impact deliverability. Sending unwanted or duplicate content annoys recipients, leading to spam reports and unsubscribes. This can cause ISPs to deprioritize mail and even lead to the loss of engaged subscribers. Data management issues and list bombing further damage sender reputation. Implementing sunset policies and differentiating giveaway entries from genuine subscriptions are crucial for maintaining list hygiene and deliverability.

Key opinions

  • Recipient Annoyance: Sending duplicate content annoys recipients and can lead to spam reports and unsubscribes.
  • ISP Deprioritization: ISPs detect and deprioritize 'substantively similar' emails, potentially sending them to spam/promotions folders.
  • Data Management: Duplicate sign-ups with the same email may indicate data management issues.
  • Loss of Engaged Subscribers: Aggressive duplicate mailing can result in the loss of highly engaged subscribers who unsubscribe.
  • List Bombing Impact: List bombing (subscribing an address to many lists without consent) harms sender reputation and deliverability.
  • Sunset Policies: Sunset policies (removing inactive subscribers) are essential for maintaining engagement and deliverability.

Key considerations

  • Consent: Ensure recipients genuinely want multiple copies of communications.
  • Spam Reports: Monitor and address spam reports resulting from duplicate mailing.
  • Content Differentiation: Differentiate giveaway entries from actual email subscriptions.
  • Reputation Damage: Recognize that sending similar messages to a user multiple times can make your email program resemble spam-like behavior, damaging reputation.
  • List Hygiene: Maintaining list hygiene by removing inactive subscribers will help avoid sending the same email to unresponsive addresses repeatedly.
Expert view

Expert from Word to the Wise explains that list bombing, where an email address is subscribed to multiple lists without consent, damages sender reputation and deliverability. Avoiding this practice is crucial.

June 2022 - Word to the Wise
Expert view

Expert from Email Geeks suggests that if sign-ups with the same email address are occurring, there might be data management issues. If it's different email addresses, users know what they are signing up for.

December 2021 - Email Geeks

What the documentation says
3Technical articles

Maintaining a low spam rate and positive sender reputation are critical for email deliverability. Sending unwanted emails, including duplicates, violates email standards and negatively impacts sender reputation, increasing the likelihood of emails being classified as junk or spam. Respecting recipient preferences and adhering to email standards is essential.

Key findings

  • Low Spam Rates: Keeping spam rates low (below 0.1%) is essential for maintaining deliverability.
  • Sender Reputation: A positive sender reputation is crucial for ensuring emails reach the inbox.
  • Unwanted Emails Impact: Sending unwanted emails, including duplicates, negatively impacts sender reputation.
  • Classification as Junk: Harm to sender reputation can lead to emails being classified as junk or spam.
  • Email Standard: Sending practices should respect the recipient and abide by email standards.

Key considerations

  • Recipient Preferences: Respect recipient preferences by only sending repeated emails if requested.
  • Compliance with Standards: Adhere to email standards to ensure proper deliverability and avoid being flagged as spam.
  • Sender Score Monitoring: Actively monitor sender reputation to identify and address issues impacting deliverability.
Technical article

Documentation from Microsoft Learn shares that a positive sender reputation is crucial for deliverability. Sending duplicate or unwanted emails can harm your reputation, leading to emails being classified as junk.

July 2022 - Microsoft Learn
Technical article

Documentation from Gmail Help indicates that keeping spam rates low (below 0.1%) is essential for maintaining deliverability. Sending unwanted emails, including duplicates, can negatively impact your sender reputation.

May 2024 - Gmail Help