Summary
A sudden spike in spam rates across multiple clients can be alarming, especially when established best practices are in place. This scenario often points to nuanced issues beyond simple content problems or list hygiene, requiring a deeper dive into traffic sources, technical configurations, and how email providers (like Gmail) interpret sending behavior and user engagement. It's crucial to understand that even minor shifts in audience or data reporting can manifest as significant deliverability challenges.
Key findings
- Client-specific spikes: Spikes affecting only certain clients suggest specific underlying issues rather than a universal change in reporting by mail providers.
- Volume thresholds: Gmail Postmaster Tools might not display IP addresses for days with very low email volume, potentially distorting the perceived spam complaint rate for a small sample of emails. This can lead to a sudden spike in spam rate on days with no actual campaigns, as the base volume is too small.
- New traffic sources: New acquisition channels, such as TikTok, can introduce traffic that is less tolerant of emails or is susceptible to bot sign-ups, leading to higher complaints.
- Welcome flow issues: High spam complaints originating from welcome flows, even with opted-in users, can indicate issues like delayed sending (where recipients forget opting in) or poor CAPTCHA implementation allowing bots to sign up.
- Authentication health: While DKIM compliance may appear 100% in Postmaster Tools, reviewing DMARC reports can provide deeper insights into authentication issues or potential DKIM replay attacks.
Key considerations
- Assess relative complaint rates: A low number of emails sent can make a few spam complaints appear as a high percentage, so consider the overall volume when interpreting rates.
- Verify traffic sources: Implement robust monitoring for new acquisition channels to identify and mitigate bot or low-quality traffic. Some online marketers suggest that spambots can incorrectly inflate traffic metrics, which could then lead to list quality issues.
- Review welcome sequence: Ensure welcome emails are sent promptly after sign-up and that their content clearly reminds recipients of their opt-in, mitigating influxes of spam complaints.
- Strengthen bot protection: Double-check CAPTCHA configurations and consider moving from single opt-in to double opt-in to prevent invalid or bot-generated email addresses from entering your lists.
- Monitor IP reputation: Although IPs might not be listed for low-volume days, consistent monitoring of your sending IP reputation remains vital.
What email marketers say
Email marketers often find themselves perplexed by sudden spam rate increases, particularly when their standard practices, such as using verification tools and maintaining consistent send volumes, haven't changed. The conversation among marketers typically revolves around identifying external factors or subtle shifts in user behavior that could be contributing to these unexpected spikes, even for seemingly legitimate email flows like welcome sequences.
Key opinions
- Unexpected welcome flow complaints: Marketers frequently express surprise when their welcome emails, typically sent to engaged subscribers, generate high spam complaints, suggesting an issue beyond content.
- Bot traffic suspicion: There's a strong inclination among marketers to attribute sudden spikes to bot traffic, especially when new acquisition channels are involved or existing CAPTCHA measures are questioned.
- Consistency of metrics: Many marketers note that while Google Postmaster Tools might show spikes, other platforms (like Klaviyo) report consistent metrics, leading to questions about reporting discrepancies.
- No overt changes: A common sentiment is that no significant changes in sending volume, list segmentation, or cadence have occurred, making the spikes particularly puzzling.
Key considerations
- Review CAPTCHA implementation: Marketers should diligently re-check their CAPTCHA settings on all forms to ensure they are configured correctly and effectively deterring bot sign-ups. Incorrect settings can lead to bot-driven traffic spikes.
- Consider double opt-in: Even with existing verification tools, switching to confirmed opt-in (double opt-in) is a strong consideration to further validate subscribers and reduce bot-generated sign-ups, particularly for new traffic sources.
- Analyze new channels: Investigate the quality of leads and sign-ups from newer marketing channels (e.g., TikTok) as they may contribute to lower engagement or higher complaint rates from less tolerant audiences.
- Content and timing of welcome emails: Despite a history of success, re-evaluating the content and timing of welcome flows might reveal opportunities to improve immediate engagement and reduce complaints. For more information, see our guide on why emails go to spam.
Marketer view
Email marketer from Email Geeks observes consistent metrics from other providers but not from Gmail. They state they do not have a Google Postmaster Tools equivalent at other providers, but Klaviyo reported metrics all seem to be consistent.
Marketer view
Email marketer from Email Geeks describes a puzzling situation with high spam complaints from welcome flows. They note that this is super strange, considering people opt-in for these emails, and the welcome flow has been successful for over a year.
What the experts say
Deliverability experts dissect sudden spam rate spikes by focusing on detailed data analysis and the intricacies of mail server interactions. Their insights often highlight the interplay between sending volume, specific traffic sources, and authentication health, guiding marketers toward comprehensive troubleshooting strategies. They emphasize that such spikes are rarely isolated incidents and often point to systemic issues needing careful investigation.
Key opinions
- Consistency indicates reporting: If a spam rate spike is not consistent across all clients, it suggests a specific issue rather than a broad change in how mail providers are reporting.
- Impact of low volume: Experts acknowledge that low email sending volumes can cause inflated spam complaint rates in Google Postmaster Tools because if the volume for an IP falls below a certain threshold, it won't appear, making any complaints seem disproportionately high.
- Traffic source scrutiny: There's a strong emphasis on closely examining traffic from new or specific sources, such as TikTok, as they might be a source of problematic email addresses (e.g., old or bot-generated). This can lead to a sudden drop in Gmail deliverability.
- DKIM replay attacks: While less common for multiple clients simultaneously, experts point to DKIM replay attacks as a potential cause for unusual activity in DKIM volume reports.
Key considerations
- Analyze overall deliverability: Beyond spam rates, investigate if overall email delivery (inbox placement vs. filtered) has decreased, as this can cause a relative increase in the spam complaint percentage.
- Segment by traffic source: Consider creating separate subdomains for email streams originating from different traffic sources (e.g., TikTok). This allows for granular monitoring of metrics in Postmaster Tools and helps isolate potential reputation issues, as discussed in our article how to improve domain reputation.
- DMARC report review: Regularly check DMARC aggregate reports for any anomalies that might suggest authentication issues or unauthorized sending, which could contribute to blocklisting or spam placement.
- Holistic metric review: Look at all available metrics—bounce rates, open rates, click-through rates, and complaint rates—across all providers to identify any correlating trends. Sometimes, what looks like a spam spike is a symptom of broader engagement issues.
Expert view
Deliverability expert from Email Geeks suggests that if a spam rate spike was due to a reporting change, it would likely be consistent across all clients. The fact that it's only affecting certain clients indicates a more specific issue that requires targeted investigation.
Expert view
Deliverability expert from Email Geeks advises looking at the DKIM volume page, as this is sometimes related to DKIM replay attacks. They acknowledge that affecting multiple clients simultaneously is unusual for such attacks.
What the documentation says
Official documentation from leading email providers and industry bodies sets the foundational guidelines for email deliverability. These resources typically outline critical technical requirements, best practices for sender reputation, and how various metrics are calculated and should be interpreted. Understanding these documented standards is essential for diagnosing and resolving complex deliverability issues like sudden spam rate spikes.
Key findings
- Spam rate definition: Documentation specifies that spam rate metrics (e.g., in Google Postmaster Tools) typically include both direct user spam reports and emails automatically classified as spam by the provider's filters.
- Volume dependency: Many tools only provide data or apply reputation thresholds when a sufficient volume of emails is sent, meaning low-volume sending can affect the visibility of IP or domain reputation data.
- Authentication importance: Standard documentation consistently emphasizes the critical role of SPF, DKIM, and DMARC in authenticating emails and building sender trust. A foundational guide to these can be found on our site in A simple guide to DMARC, SPF, and DKIM.
- Content and engagement: Beyond technical aspects, documentation frequently highlights that engaging content, relevant targeting, and proper list hygiene are essential to minimizing user complaints and maintaining positive sender reputation.
Key considerations
- Adhere to sender guidelines: Refer to and strictly follow guidelines provided by major mailbox providers, such as Google's Email Sender Guidelines, to ensure compliance with their evolving requirements.
- Understand reporting thresholds: Be aware that data in Postmaster Tools and similar platforms might not be comprehensive for very low sending volumes, which can create a misleading picture of your spam rate. This is particularly relevant when observing spam spikes in Google Postmaster Tools.
- Leverage DMARC reports: Regularly review DMARC aggregate and forensic reports to gain deeper insights into email authentication results and potential unauthorized sending activities that could impact your reputation.
- Maintain consistent sending practices: Documentation often advises maintaining consistent email sending volumes and cadences, as irregular patterns can be a red flag for spam filters.
Technical article
Documentation from Google Postmaster Tools states that the spam rate displayed reflects the percentage of emails sent to active Gmail users that are marked as spam. This includes both instances where users explicitly mark an email as spam and emails that Gmail's AI filters automatically classify as spam.
Technical article
Documentation from DMARC.org explains that DMARC reports provide senders with crucial feedback on their email authentication status, including SPF and DKIM alignment. These reports are vital for identifying if legitimate emails are failing authentication checks, which can significantly impact deliverability and lead to spam placement.
Related resources
9 resources
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