Why is there a sudden spam rate spike across multiple clients?

Summary

Sudden spam rate spikes across multiple clients are complex, stemming from diverse factors. These include specific client-level issues like changes in delivery rates, potential DKIM replay attacks, or problems linked to traffic sources like TikTok; general deliverability aspects like poor list hygiene, compromised accounts, problematic content, shared IP issues, volume spikes without warmup, referral traffic intolerance, unsuppressed bounces, irrelevant content, and sender reputation drops; and technical aspects such as authentication failures (SPF, DKIM, DMARC), non-compliance with DMARC, and ignored Feedback Loops. External factors like snowshoe spam targeting client lists or poorly managed new traffic sources also contribute. Successfully addressing this issue involves consistent monitoring, proactive troubleshooting of technical setups, strategic content review, robust list management, and careful handling of traffic sources.

Key findings

  • Client-Specific Problems: Issue may affect only some clients due to issues like changes in delivery, DKIM attacks, or TikTok traffic.
  • List Hygiene Neglect: Poor list hygiene like inactive subscribers and unsuppressed bounces increases complaints.
  • Authentication Issues: Incorrect SPF, DKIM, DMARC cause authentication failures leading to spam classification.
  • Compromised Accounts Risk: Compromised accounts sending large email volumes lead to sharp increases in complaint rates.
  • Content Based Filtering: Specific phrases or HTML structures in email copy may trigger spam filters.
  • Shared IP Damage: If using a shared IP, the deliverability of other users will affect your sending reputation.
  • Volume Increase without Warmup: Spam complaints rise sharply following sudden sending volume increases without proper warming.
  • Irrelevant Content Problems: Sending untargeted, irrelevant content can lead to users marking emails as spam.
  • Sender Reputation Drops: A sudden drop in sender reputation often causes spam filtering.
  • Missing Postmaster Data: High complaint rates without identified IPs suggest a significant volume drop below monitoring thresholds.
  • Unoptimized Welcome Emails: If welcome emails get marked as spam there are is likely a problem with content and signup process.
  • Ignored Feedback Loops: Ignoring feedback loops increases complaints over time.
  • Poor New Traffic Source Control: New or unmanaged traffic causes higher spam rates.
  • External Spam Influence: A client can be specifically targeted by spam even if you do everything correctly.

Key considerations

  • Delivery Rate Analysis: See if there are decreased inbox delivery rates for affected clients.
  • Implement a Regular Authentication Process: Regularly test Authentication setups.
  • Implement a Regular Data Cleansing Strategy: Keep lists cleaned of old emails.
  • Implement Content Code Review Processes: Test email design before sending.
  • IP Infrastructure: Have a dedicated IP address where possible.
  • Control Traffic: Be very careful when adding new referral sources.
  • Warm up Traffic: Make sure warm up is being completed when sending new emails or traffic.
  • Optimize Emails for Specific Audience: Review all emails before sending and optimize.
  • Check Your Sender Reputation: Test sending to your personal email address and have a look at how it shows up.
  • Implement Signup Validation: Review signup and authentication emails.
  • Track Feedback Loops: Sign up for Feedback Loops.
  • Investigate Traffic Sources: Double check all your traffic sources before sending.
  • Implement Spam Mitigation: Implement anti-spam solutions.

What email marketers say
12Marketer opinions

A sudden spam rate spike across multiple clients can be attributed to various factors, ranging from technical issues to content-related problems and list management practices. Several email marketers recommend checking for poor list hygiene, compromised accounts, problematic content, shared IP issues, sudden volume increases without proper warmup, referral traffic sign-ups, suppressed bounced addresses, irrelevant content, and sender reputation drops. Addressing these areas can help mitigate spam complaints and improve deliverability.

Key opinions

  • List Hygiene: Poor list hygiene, including inactive or unengaged subscribers, contributes to increased spam rates.
  • Compromised Accounts: Compromised accounts sending large volumes of spam can cause sudden spikes.
  • Content Issues: Specific words, phrases, or HTML structures in email content can trigger spam filters.
  • Shared IP Reputation: Poor practices of other senders on shared IPs impact your reputation.
  • Volume Warmup: Dramatic increases in sending volume without proper warmup trigger spam filters.
  • Referral Traffic: High volume of sign-ups from marketing campaign traffic, can trigger spam complaints.
  • Bounced Addresses: Not suppressing bounced addresses or hard bounces can damage sender reputation.
  • Segmentation Issues: Irrelevant content sent to broad audience segments increases spam complaints.
  • Sender Reputation: A sudden drop in sender reputation triggers spam filters.
  • Volume Anomaly: The absence of IP identification for spam complaints might indicate a drop in email volume below reporting thresholds.
  • Welcome Emails: High spam rates related to welcome emails could indicate issues with email content, signup processes, or CAPTCHA.

Key considerations

  • Clean Lists: Regularly clean your lists of inactive or unengaged subscribers.
  • Monitor Accounts: Monitor account activity and implement stricter password policies.
  • Review Content: Review email content and code for potential spam triggers.
  • IP Strategy: Consider dedicated IPs or closely monitor shared IP reputation.
  • Warmup Sending: Gradually ramp up sending volume when increasing sending capacity.
  • Referral Traffic strategy: Analyze referral traffic to see if that is the cause of complaints.
  • Address Suppression: Remove hard bounces immediately from sending lists.
  • Improve Segmentation: Refine segmentation and targeting strategies to send relevant content.
  • Reputation Monitoring: Monitor your sender reputation and address any underlying issues promptly.
  • Traffic Analysis: Investigate new or unknown traffic sources for potential issues.
  • Welcome Email Optimization: Check and optimize welcome email content, signup timing, and CAPTCHA implementation.
Marketer view

Email marketer from Email Geeks suggests that if a high spam complaint rate coincides with no IP identification, it could indicate a drop in email volume below Gmail Postmaster's reporting threshold, where smaller email samples might skew complaint rates higher.

April 2022 - Email Geeks
Marketer view

Email marketer from Gmass explains that spam complaints can be triggered due to a high volume of sign-ups from a particular marketing campaign, with this new referral traffic being less tolerant to email.

January 2024 - Gmass
Marketer view

Email marketer from Reddit responds that compromised accounts can suddenly send out large volumes of spam, causing spikes. Monitor account activity and implement stricter password policies.

April 2021 - Reddit
Marketer view

Email marketer from Litmus states that dramatically increasing sending volume without proper warmup can trigger spam filters and cause complaint spikes. Ramp up sending gradually.

April 2024 - Litmus
Marketer view

Email marketer from Email on Acid explains that certain words, phrases, or HTML structures can trigger spam filters. Review your email content and code for potential issues.

June 2024 - Email on Acid
Marketer view

Email marketer from Email Geeks suggests splitting email streams into different subdomains to monitor stats in Gmail postmaster, which requires warming up a new subdomain.

December 2021 - Email Geeks
Marketer view

Email marketer from HubSpot suggests that sending irrelevant content to a large segment of your audience can lead to more spam complaints. Improve segmentation and targeting strategies.

April 2021 - HubSpot
Marketer view

Email marketer from Mailchimp Community shares that sudden spam spikes often correlate with poor list hygiene. Ensure you're regularly cleaning your list of inactive or unengaged subscribers.

April 2022 - Mailchimp Community
Marketer view

Email marketer from Email Geeks suggests that welcome emails marked as spam are a red flag. Suggests checking email content, signup time delay, CAPTCHA functionality, and considering switching to confirmed opt-in.

December 2024 - Email Geeks
Marketer view

Email marketer from StackOverflow explains that if using a shared IP, another sender's poor practices can impact your reputation, leading to spam spikes. Consider dedicated IPs or monitor shared IP reputation.

April 2024 - StackOverflow
Marketer view

Email marketer from Sendgrid shares a problem can arise if you haven't suppressed bounced addresses. Email marketers need to remove hard bounces from sending lists immediately. Sending to invalid email addresses increases the likelihood of being flagged as a spammer, thus increasing spam rates.

January 2025 - Sendgrid
Marketer view

Email marketer from ReturnPath explains that a sudden drop in sender reputation can trigger spam filters. Monitor your reputation and address any underlying issues.

December 2023 - ReturnPath

What the experts say
5Expert opinions

Sudden spam rate spikes across multiple clients can stem from various underlying issues. Experts suggest investigating specific problems affecting certain clients, such as changes in delivery rates, potential DKIM replay attacks, or issues related to traffic from sources like TikTok. It may also indicate damage to sender reputation, potentially due to snowshoe spam tactics, authentication problems, poor list hygiene, content issues, or feedback loop neglect. Addressing such issues requires examining authentication, traffic sources, and overall sender practices to mitigate spam complaints.

Key opinions

  • Delivery Changes: Decreased inbox delivery rates can cause relative increases in spam complaint rates.
  • DKIM Replay Attacks: DKIM volume page should be checked for potential DKIM replay attacks.
  • Traffic Source Problems: Traffic from sources like TikTok may have specific deliverability issues.
  • Sender Reputation Damage: Spam spikes can indicate damage to sender reputation, especially in shared infrastructures.
  • Snowshoe Spam: Snowshoe spam tactics can temporarily inflate spam complaints.
  • Poorly Managed Traffic Sources: New, unknown, or poorly managed traffic sources increases the risk of complaints.

Key considerations

  • Investigate Delivery: Determine if delivery rates to inboxes have changed for affected clients.
  • Check DKIM Volume: Review DKIM volume pages for signs of replay attacks.
  • Analyze TikTok Traffic: Identify and analyze traffic signatures from TikTok for potential issues.
  • Monitor Reputation: Implement reputation monitoring and address damages on time.
  • Authentication Check: Implement and test authentication on email.
  • List Hygiene: Implement and test data quality of email.
  • Monitor Traffic Sources: Implement and test all the sources of email and campaigns.
  • Warming Strategies: Implement and test warm up and traffic patterns.
Expert view

Expert from Word to the Wise explains that a sudden spam rate spike could be a signal that something is damaging your sender reputation, particularly if the infrastructure is shared among multiple clients. Things to check are authentication, list hygiene, content and complaint feedback loops.

September 2024 - Word to the Wise
Expert view

Expert from Spam Resource shares that snowshoe spam, which involves sending spam from a wide range of IP addresses and domains, can cause temporary spikes in spam complaints if spammers target specific client lists. Also he explains that sudden spam spikes can occur when new, unknown, or poorly managed traffic sources are integrated without proper warming or monitoring. Such traffic often carries a higher spam complaint rate initially.

August 2021 - Spam Resource
Expert view

Expert from Email Geeks suggests looking closely at TikTok traffic as a potential source of the problem, citing previous issues with Facebook signups due to old addresses. Recommends identifying and analyzing the specific traffic for any fixable issues.

June 2021 - Email Geeks
Expert view

Expert from Email Geeks suggests that because the issue isn't consistent across all clients, it indicates a specific problem. She recommends investigating if delivery has changed and whether fewer recipients are receiving emails in their inbox, potentially causing a relative increase in complaint rates.

October 2023 - Email Geeks
Expert view

Expert from Email Geeks advises to check the DKIM volume page for potential DKIM replay attacks, while noting the unusual nature of multiple clients being affected simultaneously.

May 2023 - Email Geeks

What the documentation says
5Technical articles

Sudden spam rate spikes across multiple clients are attributed to a range of issues, including changes in user behavior, content problems, authentication failures, compromised accounts, list bombing, and non-compliance with email authentication standards like SPF, DKIM, and DMARC. Neglecting Feedback Loops (FBLs) and failing to monitor sender reputation can also contribute. Documentation emphasizes the importance of regular monitoring using tools like Google Postmaster Tools and Microsoft SNDS, validating authentication settings, and correctly implementing DMARC policies.

Key findings

  • User Behavior: Changes in user behavior can lead to increased spam complaints.
  • Content Problems: Issues with email content trigger spam filters.
  • Authentication Failures: Incorrect SPF, DKIM, or DMARC configurations lead to authentication failures.
  • Compromised Accounts: Compromised accounts can cause sudden increases in spam.
  • List Bombing: List bombing activities contribute to spam complaints.
  • Non-Compliance with DMARC: Non-compliance with DMARC policies results in email rejection or spam marking.
  • Ignoring Feedback Loops: Ignoring Feedback Loops leads to increased spam complaints.

Key considerations

  • Monitor Sending Reputation: Regularly monitor sending reputation using tools like Google Postmaster Tools.
  • Review Sender Data: Analyze Sender Reputation Data (SNDS) for anomalies.
  • Validate Authentication Settings: Regularly validate SPF, DKIM, and DMARC configurations.
  • Implement DMARC Policies: Correctly implement and monitor DMARC records.
  • Utilize Feedback Loops: Monitor and act on information from Feedback Loops (FBLs).
Technical article

Documentation from Google explains that sudden spam rate spikes can be due to changes in user behavior, content issues, or authentication problems. Monitor your sending reputation in Postmaster Tools for insights.

September 2022 - Google
Technical article

Documentation from DMARC.org answers that non-compliance with DMARC policies can lead to email rejection or being marked as spam. Correctly implement and monitor your DMARC records.

January 2022 - DMARC.org
Technical article

Documentation from RFC Editor explains that incorrect SPF, DKIM, or DMARC configurations can lead to authentication failures, increasing the likelihood of emails being marked as spam. Regularly validate your authentication settings.

April 2023 - RFC Editor
Technical article

Documentation from Microsoft explains that a sudden increase in spam complaints could be attributed to compromised accounts, list bombing, or content issues. Review your Sender Reputation Data (SNDS) for anomalies.

April 2023 - Microsoft
Technical article

Documentation from SparkPost explains that Feedback Loops (FBLs) provide information from ISPs about users marking emails as spam. Ignoring FBLs can lead to increased spam complaints over time.

March 2021 - SparkPost