Summary
A sudden spike in spam rates for opted-in subscribers across multiple subdomains is a complex issue with numerous potential causes. These include changes in email content, compromised IP addresses, poor list hygiene, shared IP issues, changes in feedback loop data, domain and sender reputation problems, poorly coded HTML emails, sudden increases in email frequency, the use of spam trigger words, referral spam, email list bombing, inadequate permission practices, and low engagement rates. Additionally, anecdotal evidence suggests that email providers might be adjusting their spam calculation algorithms. Technical factors like failure to properly authenticate emails using SPF, DKIM, and DMARC and updates to content filters by email providers also contribute. Monitoring and addressing these areas is critical to maintaining good deliverability.
Key findings
- Content Changes: Sudden changes in email content, keywords, links, or structure can trigger spam filters.
- IP Reputation: Compromised IP addresses or sudden changes in sending volume can lead to spam spikes.
- List Hygiene: Poor list hygiene with inactive or invalid addresses increases spam rates.
- Shared IP Issues: Using a shared IP address means others' spam practices can affect deliverability.
- FBL Data: Changes in feedback loop data indicate spam complaint issues.
- Domain Reputation: Blacklisted or poor domain reputation leads to higher spam rates.
- Sender Reputation: Drops in sender reputation tracked by ISPs increases spam rates.
- HTML Coding: Poorly coded HTML triggers spam filters.
- Email Frequency: Sudden increases in email frequency without warming up the list lead to spam complaints.
- Spam Words: Using spam trigger words in email copy can increase spam classification.
- Referral Spam: Referral spam can distort engagement metrics, leading to deliverability issues.
- List Bombing: Email list bombing attacks increase spam complaints and potential blacklisting.
- Permission: Lack of verifiable permission and poor list hygiene increase spam complaints and hurt deliverability.
- Engagement: Low engagement rates negatively impact sender reputation, increasing the likelihood of emails being marked as spam.
- Authentication: Failing to authenticate emails with SPF, DKIM, and DMARC increases spam rates.
- Filters: Updates to content filters can result in increased spam detection.
- Calculation Tinkering: Email providers might be adjusting their spam calculation algorithms.
- Spam Rate Threshold: Google emphasizes keeping spam rates below 0.3% for Gmail deliverability.
Key considerations
- Content Review: Regularly review email content for potential spam triggers.
- IP Monitoring: Monitor IP reputation and sending volume.
- List Cleaning: Maintain a clean and engaged email list.
- Sender Reputation Monitoring: Monitor sender reputation with email providers.
- HTML Testing: Test HTML code to ensure proper coding standards.
- Frequency Planning: Gradually increase email frequency.
- Traffic Monitoring: Monitor referral traffic and filter out invalid sign-ups.
- Attack Defense: Implement robust defenses against email list bombing attacks.
- Implement Authentication: Implement SPF, DKIM, and DMARC authentication.
- Tools: Use deliverability testing tools before sending emails.
- Protocols: Ensure emails are adhering to all relevant email deliverability protocols.
- Feedback Loops: Monitor Feedback Loops to stay aware of complaint surges.
- Engagement data: Email service providers value email engagement metrics which help indicate the quality of the content to their users.
What email marketers say
13 marketer opinions
A sudden spike in spam rates for opted-in subscribers across multiple subdomains can be attributed to a variety of factors. These include changes in email content, compromised IP addresses or sudden changes in sending volume, poor list hygiene, issues with shared IP addresses, changes in feedback loop data, domain or sender reputation problems, poorly coded HTML emails, sudden increases in email frequency, and the use of spam trigger words. Additionally, anecdotal evidence suggests potential tinkering with spam calculation algorithms by email providers.
Key opinions
- Content Changes: Sudden changes in email content (keywords, links, structure) can trigger spam filters.
- IP Reputation: Compromised IP addresses or sudden changes in sending volume can lead to spam spikes.
- List Hygiene: Poor list hygiene (inactive/invalid addresses) increases spam rates.
- Shared IP Issues: Using a shared IP address means others' spam practices can affect your deliverability.
- FBL Data: Changes in feedback loop data indicate spam complaint issues.
- Domain Reputation: Blacklisted or poor domain reputation leads to higher spam rates.
- Sender Reputation: Drops in sender reputation (tracked by ISPs) increases spam rates.
- HTML Coding: Poorly coded HTML triggers spam filters.
- Email Frequency: Sudden increases in email frequency without warming up the list lead to spam complaints.
- Spam Words: Using spam trigger words in email copy can lead to increased spam classification.
- Algorithm Tinkering: Anecdotal evidence suggests email providers might be adjusting their spam calculation algorithms.
Key considerations
- Content Review: Regularly review email content for potential spam triggers.
- IP Monitoring: Monitor IP reputation and sending volume.
- List Cleaning: Maintain a clean and engaged email list.
- Sender Reputation Monitoring: Monitor your sender reputation with email providers.
- HTML Testing: Test HTML code to ensure proper coding standards.
- Frequency Planning: Gradually increase email frequency.
- Authentication Protocols: Implement authentication protocols to allow mail servers to verify that a message really did come from the domain it claims to have come from.
- Engagement data: Email service providers value email engagement metrics which help indicate the quality of the content to their users.
Marketer view
Email marketer from Campaign Monitor states that spam filters trigger on words that are considered spam. Make sure to avoid using these spam words in your email copy. URL: https://www.campaignmonitor.com/resources/glossary/spam-filters/
2 Jun 2022 - Campaign Monitor
Marketer view
Email marketer from HubSpot shares that if you suddenly increase the frequency of your emails without warming up your audience, it can lead to higher spam rates. Gradual increase of email frequency is best. URL: https://blog.hubspot.com/marketing/email-deliverability
15 Feb 2024 - HubSpot
What the experts say
4 expert opinions
A sudden spike in spam rates for opted-in subscribers across multiple subdomains can be triggered by referral spam skewing engagement metrics, email list bombing attacks overwhelming recipients, inadequate permission practices affecting list quality, and low engagement rates diminishing sender reputation. Addressing these issues necessitates vigilant monitoring of traffic, robust defenses against attacks, strict adherence to verifiable permission protocols, and proactive efforts to boost subscriber engagement.
Key opinions
- Referral Spam: Referral spam can distort engagement metrics, leading to deliverability issues.
- Email List Bombing: Email list bombing attacks cause a surge in spam complaints, potentially leading to blacklisting.
- Verifiable Permission: Lack of verifiable permission and poor list hygiene increase spam complaints and hurt deliverability.
- Engagement Data: Low engagement rates negatively impact sender reputation, increasing the likelihood of emails being marked as spam.
Key considerations
- Traffic Monitoring: Vigilantly monitor referral traffic to identify and filter out invalid or bot-generated sign-ups.
- Attack Defense: Implement robust defenses against email list bombing attacks.
- Permission Protocols: Adhere to strict verifiable permission protocols to ensure subscribers have explicitly consented to receive emails.
- Engagement Improvement: Proactively work to improve subscriber engagement metrics (open rates, click-through rates) to maintain good deliverability.
Expert view
Expert from SpamResource explains that referral spam can indirectly impact your deliverability, especially if it leads to skewed engagement metrics or inaccurate list data. Monitoring referral traffic and taking steps to filter out invalid or bot-generated sign-ups is crucial for maintaining list quality and preventing spam issues.
17 Jul 2023 - SpamResource
Expert view
Expert from Word to the Wise explains the importance of verifiable permission and proper list hygiene practices. Maintaining a clean and engaged subscriber list can greatly reduce the risk of spam complaints and improve overall deliverability. Reviewing your subscription process and ensuring that you have explicit consent from subscribers can help prevent spam issues.
9 May 2023 - Word to the Wise
What the documentation says
4 technical articles
A sudden spike in spam rates can stem from several technical factors. Google emphasizes maintaining spam rates below 0.3% and using Postmaster Tools for monitoring. Failure to properly authenticate emails with SPF, DKIM, and DMARC as outlined by RFC guidelines contributes to increased spam rates. Microsoft's Exchange Online Protection (EOP) uses content filters that, when updated, can lead to increased spam detection. Utilizing deliverability testing tools, like GlockApps, can proactively identify content, authentication, or reputation issues.
Key findings
- Spam Rate Threshold: Google emphasizes keeping spam rates below 0.3% for Gmail deliverability.
- Email Authentication: Failing to authenticate emails with SPF, DKIM, and DMARC increases spam rates.
- Content Filters: Updates to content filters in Microsoft's EOP can increase spam detection.
- Deliverability Testing: Deliverability testing tools can identify issues with content, authentication, or IP reputation.
Key considerations
- Spam Rate Monitoring: Monitor spam rates using Google Postmaster Tools.
- Authentication Implementation: Implement and verify SPF, DKIM, and DMARC authentication.
- Deliverability Testing: Use deliverability testing tools before sending emails.
- Email protocols: Ensure emails are adhering to all relevant email deliverability protocols.
Technical article
Documentation from Microsoft explains that Exchange Online Protection (EOP) uses content filters that analyze email content for characteristics indicative of spam. Changes to these filters or the introduction of new rules can result in a sudden increase in spam detection. URL: https://learn.microsoft.com/en-us/microsoft-365/security/office-365-security/anti-spam-policies-configure?view=o365-worldwide
2 Apr 2024 - Microsoft
Technical article
Documentation from RFC explains that failing to properly authenticate emails using SPF, DKIM, and DMARC can lead to increased spam rates. Implementing and verifying these authentication methods is crucial for ensuring that your emails are trusted by email providers. Incorrect or missing authentication records can cause deliverability issues. URL: https://www.rfc-editor.org/
19 Aug 2024 - RFC-Editor
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