How can I improve email deliverability for large emails with many images and links when experiencing high spam complaint rates?

Key findings

• Content size secondary: Email size and the number of images or links are typically not the primary cause of deliverability issues, unlike what many might assume. Instead, the real culprits often involve subscriber engagement and consent.
• Spam complaints are critical: High spam complaint rates are a strong indicator of poor sender reputation and are a direct cause of emails going to spam or being blocked. These complaints frequently arise when recipients feel they did not explicitly opt in or are receiving irrelevant content.
• Gmail clipping: Large HTML sizes (e.g., over 102KB for Gmail) can lead to email clipping, where parts of the email (including the unsubscribe link) are hidden, forcing frustrated recipients to mark the email as spam rather than simply unsubscribing. This indirectly impacts deliverability.
• Authentication is foundational: Proper email authentication, such as SPF, DKIM, and DMARC, is crucial for establishing sender legitimacy. However, even with correct technical setup, poor sending practices can still harm reputation.
• Engagement matters most: Internet service providers (ISPs) heavily weigh subscriber engagement when determining inbox placement. Low engagement, coupled with high complaints, signals that subscribers do not want the emails.

Key considerations

• Review opt-in processes: Implement or reinforce clear, positive opt-in strategies, such as double opt-in, to ensure recipients genuinely want to receive your emails. This helps reduce spam complaints at the source. For more details on this, read our article on how spam complaints can impact deliverability.
• Optimize unsubscribe placement: Ensure the unsubscribe link is easily visible and accessible, ideally at the top or in a prominent area, rather than hidden in a clipped footer. This allows users to opt out gracefully instead of marking as spam.
• Segment and re-engage: Segment your list and send large, image-heavy emails only to highly engaged subscribers. For less engaged contacts, consider a re-engagement campaign with simpler content or remove them if they remain unresponsive.
• Content and image optimization: While not the primary issue, optimizing image sizes and HTML can improve user experience and reduce clipping. Avoid putting essential text solely within images, as this can trigger spam filters and hinder accessibility. Customer.io provides useful insights into email deliverability best practices including advice on complaint rates.
• Monitor reputation actively: Regularly check your sender reputation using tools like Google Postmaster Tools. This can reveal trends in spam complaints, IP reputation, and domain reputation. Learn how to leverage Google Postmaster Tools to diagnose and address issues.

Key opinions

• Client resistance: Marketers frequently encounter clients who insist their long-used email formats, regardless of size or complexity, cannot be the source of new deliverability problems, making it difficult to implement necessary changes.
• Spam complaint focus: Despite initial concerns about email size, marketers find that extremely high spam complaint rates are the most evident symptom of underlying deliverability issues.
• Clipped emails impact behavior: Emails being clipped by major providers like Gmail, often due to large HTML sizes, can hide essential elements such as the footer and unsubscribe link, inadvertently driving recipients to mark emails as spam.
• Reputation is key: Many marketers conclude that deliverability struggles are primarily reputation-based, stemming from a combination of using poor lists, inconsistent sending frequency, and overall email size contributing to negative user signals.

Key considerations

• Address client perceptions: Educate clients that while size might not be a direct blocking factor, its secondary effects on user experience and complaint rates are significant for deliverability. Show them data from Google Postmaster Tools on spam complaint rates. Our guide on Google Postmaster Tools V2 can help.
• Prioritize unsubscribe visibility: Advocate for placing the unsubscribe mechanism where it is easily accessible, even if the email content is clipped. This is a critical first step to reduce spam complaints, as unhappy subscribers will opt-out rather than mark as spam.
• Implement list hygiene: Actively clean and manage email lists, especially when addresses come from various sources like open houses. Sending only to engaged contacts is crucial. This is tied to your email reputation.
• Seek explicit consent: For lists sourced from events, implement a positive opt-in process (e.g., asking "Are you interested in getting more emails?") to ensure explicit consent. Mailgun provides a great overview of best practices for improving email delivery.

Key opinions

• Email size not the culprit: Experts widely agree that the size of an email's HTML, or the cumulative size of remote images, generally does not directly affect whether an ISP places an email in the inbox or spam folder.
• Link count is often irrelevant: Having a high number of links, even 50 or more, is typically not a direct trigger for emails going to the bulk folder, especially if they are from a dedicated, consistent domain.
• User experience drives complaints: The primary issue with large emails is often the user experience, particularly when content clipping hides crucial elements like unsubscribe links, compelling users to report spam instead.
• Engagement dictates reputation: Poor or depressed engagement, often due to unclear opt-in processes or outdated subscriber lists, is a significant factor in declining deliverability and increased spam complaints.

Key considerations

• Prioritize visible unsubscribe: As a critical first step, ensure the unsubscribe option is prominently placed and easily accessible. This simple change can significantly reduce spam complaints by providing an alternative to reporting spam. Review our insights on managing unsubscribes for better deliverability.
• Strict opt-in enforcement: Only send emails, especially large or complex ones, to subscribers who have explicitly and affirmatively opted in. This ensures genuine interest and minimizes spam complaints from disengaged users.
• Comprehensive email audit: Conduct a full audit of email practices, from list acquisition to content strategy, to identify underlying issues causing depressed engagement and high complaint rates. This holistic approach can reveal issues that simple content adjustments won't fix. For guidance, see how to diagnose and improve email deliverability.
• Sender reputation management: Recognize that high spam complaints are a symptom of poor sender reputation. Focus on improving engagement metrics and maintaining clean lists to recover and sustain a positive reputation. Unspam.email highlights proven methods to boost email deliverability.

Key findings

• Complaint rates are paramount: Documentation consistently stresses that spam complaint rates are a critical metric. A rate exceeding 0.10% can severely damage sender reputation and lead to blocklisting or inbox placement issues.
• Image-heavy emails: Emails consisting solely of images, or being very image-heavy, are often flagged by spam filters. This is because spammers frequently use this technique to bypass text-based filters.
• Content to text ratio: ISPs prefer emails with a balanced text-to-image ratio. Important textual content should not be embedded only within images.
• Clipping concerns: While not directly causing spam, large email sizes can lead to clipping, which hides content and crucial links, potentially increasing spam complaints due to user frustration.

Key considerations

• Monitor spam complaint thresholds: Actively monitor your spam complaint rates and strive to keep them well below the 0.10% industry threshold. Exceeding this limit signals negative user engagement and a poor sender reputation. Our guide on Google Postmaster Tools spam rates explains this further.
• Balance content presentation: Ensure your emails have a healthy mix of text and images. Crucial information should always be in HTML text rather than solely within images, improving accessibility and deliverability. Learn how to protect deliverability for image-only emails.
• Optimize for size: While size itself is not a direct deliverability factor, compressing images and streamlining HTML can prevent clipping issues, ensuring the entire message, including the unsubscribe link, is visible. This fosters a better user experience, indirectly reducing complaints. Klaviyo's help center provides useful guidance on understanding email deliverability.
• Provide clear unsubscribe paths: Always provide a clear, one-click unsubscribe option. This aligns with industry best practices and avoids forcing recipients to mark emails as spam simply to stop receiving them.