Do spam complaints from different email domains have different weights in deliverability?

Summary

Spam complaints significantly impact email deliverability and sender reputation across various ISPs, with different email domains potentially carrying different weights. While the specific weighting algorithms are often kept secret, larger ISPs like Gmail, Outlook, and Yahoo! are generally understood to have a more significant influence due to their substantial user bases and the engagement levels of those users. High complaint rates can lead to emails being filtered to spam folders and negatively impact deliverability. The impact of spam complaints varies depending on the ISP, with some prioritizing complaints from users with a history of accurate spam reporting. It is also crucial to consider the diversity of complaints, as concentrated complaints from a single provider may indicate issues with email practices targeting that provider's users. Senders should actively monitor feedback loops to identify and address deliverability issues, maintaining compliance with ESP acceptable use policies (AUPs), and strive to keep complaint rates below acceptable thresholds (e.g., below 0.1%). The overall volume of complaints is also a key factor, with sustained high volumes harming deliverability regardless of the source.

Key findings

  • Impact: Spam complaints are a critical factor influencing email deliverability and sender reputation.
  • Weighting Factors: Larger ISPs (Gmail, Outlook, Yahoo!) likely have more influence due to user base and engagement.
  • ISP Variation: The impact of spam complaints varies between ISPs, with some prioritizing reliable reporters.
  • Complaint Diversity: Concentrated complaints from one provider may indicate targeting problems.
  • Volume Matters: Sustained high complaint volume negatively impacts deliverability, regardless of the source.
  • Secret Algorithms: Specific weighting algorithms used by ISPs are generally not made public.
  • AUP compliance: ESPs use complaints to determine if customers are violating their AUPs.

Key considerations

  • Monitor Complaints: Actively monitor spam complaint rates across different ISPs to identify and address issues promptly.
  • Prioritize Major Domains: Pay close attention to complaints from major domains like Gmail and Yahoo!.
  • Implement Best Practices: Adopt email marketing best practices to minimize spam complaints and improve engagement.
  • Address Targeting Issues: If complaints are heavily concentrated from one provider, investigate and adjust targeting practices.
  • Utilize Feedback Loops: Use feedback loops (FBLs) provided by ISPs to monitor complaints and adjust email practices.
  • Maintain Compliance: Ensure that email practices comply with ESP acceptable use policies (AUPs).
  • Minimize Complaint Rates: Strive to maintain complaint rates below acceptable thresholds (e.g., below 0.1%) to prevent deliverability issues.
  • Analyze Delivered Percentages: Analyze the complaints as percentages of total email sent and delivered to each specific ISP.

What email marketers say
9Marketer opinions

The general consensus is that spam complaints significantly impact email deliverability. While the specific weighting algorithms are typically not public, larger ISPs like Gmail and Yahoo are thought to have more influence due to their user base and the engagement levels of their users. The impact of spam complaints can vary between ISPs, and some prioritize complaints from users with a history of accurate spam reporting. Maintaining low complaint rates and monitoring complaints from major domains is crucial for avoiding blacklisting and ensuring optimal email deliverability. Additionally, the volume of complaints matters, as sustained high volumes, regardless of the source, negatively impact deliverability.

Key opinions

  • Impact: Spam complaints are a critical factor influencing email deliverability.
  • Weighting: Larger ISPs likely have more influence, with weighting depending on user engagement.
  • ISP Variation: The impact of spam complaints varies by ISP; some prioritize reliable reporters.
  • Volume Matters: Sustained high complaint volume negatively impacts deliverability.
  • Secret algorithms: Exact weighting algorithms are generally not public.

Key considerations

  • Monitor Complaints: Actively monitor spam complaint rates to identify and address issues.
  • Major Domains: Pay close attention to complaints from major domains like Gmail and Yahoo.
  • Best Practices: Implement email marketing best practices to minimize spam complaints.
  • Engagement: Focus on user engagement to reduce the likelihood of spam complaints.
  • Feedback Loops: Utilize feedback loops to monitor complaints from various ISPs.
Marketer view

Email marketer from Senderscore.org details that the volume of complaints matters a lot, and that having a sustained high volume of complaints will harm deliverability over time, regardless of the original source.

November 2023 - Senderscore.org
Marketer view

Email marketer from Quora explains that spam complaints are a direct signal to ISPs that recipients don't want to receive your emails. High complaint rates can lead to blacklisting and reduced deliverability.

September 2024 - Quora
Marketer view

Email marketer from Email Marketing Forum responds that the impact of spam complaints varies depending on the ISP. Some ISPs may prioritize complaints from users with a history of accurate spam reporting.

October 2024 - Email Marketing Forum
Marketer view

Email marketer from GlockApps shares that complaints from major domains like Gmail and Yahoo can have a larger impact due to their significant user base. Monitoring complaint rates from these domains is crucial.

March 2022 - GlockApps
Marketer view

Email marketer from Litmus shares that spam complaints are a critical factor influencing email deliverability. Litmus recommends monitoring complaint rates and implementing best practices to minimize them.

October 2021 - Litmus
Marketer view

Email marketer from StackExchange responds that while specific weights are secret, it's logical that complaints from highly engaged users on major platforms carry more weight. Focus on overall engagement.

May 2024 - StackExchange
Marketer view

Email marketer from Mailchimp explains that spam complaints are a critical factor in determining email deliverability. Mailchimp actively monitors complaints and provides feedback to users. Some ISPs may give more weight to complaints from certain domains or users.

February 2025 - Mailchimp
Marketer view

Email marketer from Neil Patel Blog explains that sender reputation is crucial, and high spam complaint rates negatively impact it. Some ISPs may weigh complaints more heavily, especially from engaged users.

May 2021 - Neil Patel Blog
Marketer view

Email marketer from Reddit shares that while the exact weighting isn't public, larger ISPs like Gmail and Yahoo likely have more influence due to their user base. Focus on keeping all complaint rates low.

May 2023 - Reddit

What the experts say
3Expert opinions

Spam complaints significantly influence email deliverability, with the weight given to each complaint varying based on the email provider and user engagement. Complaints should be viewed as a percentage of delivered emails per provider. Major providers like Gmail, Outlook, and Yahoo! consider complaints in their reputation calculations, likely giving more weight to active, engaged users. High concentrations of complaints from a single provider can signal issues with targeted email practices. Monitoring feedback loops is crucial to manage AUP compliance, with rates over 0.3% indicating problems, and acceptable rates falling below 0.1%.

Key opinions

  • Complaint Percentage: View complaints as a percentage of emails delivered to each provider.
  • Provider Influence: Major providers (Gmail, Outlook, Yahoo!) factor complaints into reputation.
  • User Engagement: Complaints from active, engaged users likely carry more weight.
  • Complaint Diversity: Concentrated complaints from one provider may indicate targeting issues.
  • AUP Compliance: ESPs use complaints to determine if customers are violating their AUP.

Key considerations

  • Monitor Feedback Loops: Actively monitor feedback loops to track spam complaints.
  • Investigate Concentrations: If complaints are heavily concentrated from one provider, investigate the cause.
  • Comply with AUP: Ensure email practices comply with ESP's acceptable use policies.
  • Acceptable Complaint Rates: Maintain complaint rates below 0.1% to remain in good standing.
  • Reputation Impact: Focus on maintaining a good sender reputation to avoid filtering.
Expert view

Expert from Spam Resource explains that large mailbox providers like Gmail, Outlook, and Yahoo! consider complaints as a factor in reputation. The weight given to a specific complaint is complex and depends on many factors, but it's reasonable to assume that complaints from active and engaged users of these providers carry more weight.

January 2022 - Spam Resource
Expert view

Expert from Word to the Wise explains that the diversity of complaints from different domains can impact your reputation. If complaints are heavily concentrated from a specific provider, it may indicate a problem with your email practices targeting that provider's users.

September 2022 - Word to the Wise
Expert view

Expert from Email Geeks explains that spam complaints should be viewed as a percentage of messages delivered to the inbox at each provider. ISPs only care about complaints for mail they see. Gmail complaints are rare because Gmail doesn't send complaints back to Klaviyo. ESPs use complaints to determine if customers violate their AUP. Complaint rates over 0.3% are generally considered bad, while rates below 0.1% are acceptable.

November 2021 - Email Geeks

What the documentation says
4Technical articles

Spam complaints significantly impact email deliverability across major email providers like Google and Microsoft. These providers utilize sender reputation systems that consider spam complaints as a key factor for filtering emails. High complaint rates lead to emails being directed to spam folders and negatively affect overall deliverability. Feedback loops (FBLs), as technically specified by RFC standards, are essential for senders to monitor spam complaints and identify deliverability issues. Different ISPs provide these FBLs to help senders address and improve their email practices.

Key findings

  • Google Impact: Spam complaints significantly impact deliverability to Gmail users, leading to spam filtering.
  • Microsoft Reputation: Microsoft's sender reputation system considers spam complaints, affecting deliverability.
  • Essential FBLs: Feedback loops (FBLs) are essential for monitoring spam complaints.
  • RFC Standards: RFC details the technical specifications for FBLs and automated spam reporting.

Key considerations

  • Monitor FBLs: Actively monitor feedback loops from different ISPs to identify issues.
  • Address Deliverability: Use FBL data to address and improve email deliverability practices.
  • Improve Reputation: Implement strategies to improve sender reputation and reduce spam complaints.
  • Avoid Spam Filters: Maintain low complaint rates to avoid being filtered to spam folders.
  • RFC Compliance: Understand and adhere to RFC standards related to feedback loops.
Technical article

Documentation from SparkPost explains that feedback loops (FBLs) are essential for monitoring spam complaints. Different ISPs provide FBLs, and the data received helps senders identify and address deliverability issues.

March 2021 - SparkPost
Technical article

Documentation from RFC details the technical specifications for feedback loops (FBLs) and automated spam reporting systems. These systems allow ISPs to provide senders with information about spam complaints.

January 2022 - RFC
Technical article

Documentation from Microsoft explains that sender reputation is based on various factors, including spam complaints. Microsoft uses this reputation to filter incoming emails, and higher complaint rates can negatively affect deliverability.

November 2022 - Microsoft
Technical article

Documentation from Google explains that spam complaints significantly impact deliverability to Gmail users. High complaint rates can lead to emails being filtered to spam folders.

September 2024 - Google