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Summary

When introducing new email templates, marketers often observe an unexpected and significant drop in Gmail open rates, even when subject lines and sender information remain consistent. This phenomenon suggests that elements within the new template's design or underlying code might be negatively impacting deliverability or how Gmail processes and displays the messages. While initial spam tests and Google Postmaster Tools might not immediately flag issues, the subtle changes in template structure, image hosting, tracking pixels, or even email size can influence how Gmail's algorithms perceive the email, potentially leading to lower inbox placement or reduced visibility.

What email marketers say

Email marketers grappling with new templates often report a perplexing drop in Gmail open rates despite maintaining consistent subject lines and sender details. Their experiences highlight how even seemingly minor alterations in template design or code can have significant, unexpected impacts on deliverability. Many suspect changes in tracking pixels, external content hosting, or hidden code elements as the culprits, pointing to Gmail's nuanced filtering mechanisms that extend beyond traditional spam checks.

Marketer view

Marketer from Email Geeks indicates they saw Gmail open rates plummet after introducing new email templates, even though sender info and subject lines remained consistent. They quickly isolated the issue to the new templates, as reverting to the old ones restored open rates.

19 Feb 2019 - Email Geeks

Marketer view

Marketer from Email Geeks observes that testing the new templates with a small audience percentage caused Gmail open rates to plummet again for that specific campaign. This pattern strongly suggests the new code as the primary culprit.

19 Feb 2019 - Email Geeks

What the experts say

Email deliverability experts highlight that while email templates might seem like a mere visual change, their underlying code and structure can significantly influence how mailbox providers, particularly Gmail, process and filter messages. They emphasize that factors beyond obvious content changes, such as hidden code, external asset loading, and tracking mechanisms, are often scrutinized. A drop in open rates after a template change suggests that some element within the new design is negatively affecting Gmail's trust signals or its ability to correctly render and deliver the email to the primary inbox.

Expert view

Expert from Spam Resource suggests that even minor code changes, particularly in how images or links are rendered, can subtly influence spam filters. These filters evaluate not just content but also the underlying technical structure.

10 Apr 2024 - Spam Resource

Expert view

Expert from Word to the Wise observes that sudden shifts in email formatting or structure can sometimes trigger algorithmic responses from mailbox providers, classifying previously benign mail as potentially less desirable, impacting delivery to the inbox.

05 May 2024 - Word to the Wise

What the documentation says

Official documentation and email standards outline various technical aspects that can influence email deliverability and how content is parsed by mailbox providers. While open rates are a user engagement metric, their drop often points to underlying technical or compliance issues. Specifications like RFCs for email formatting, HTML rendering best practices, and sender guidelines from major mailbox providers (like Gmail) all contribute to how emails are judged. Deviations in new templates from these subtle or explicit rules, particularly in areas like MIME structure, image loading, or embedded tracking mechanisms, can lead to negative deliverability outcomes without triggering overt error messages.

Technical article

Email Standards Documentation emphasizes that valid HTML structure is critical for consistent rendering across email clients. Poorly constructed or non-standard HTML can lead to unexpected display issues or trigger spam filters, impacting deliverability.

15 Feb 2024 - W3C HTML Email Best Practices

Technical article

Mailbox Provider Guidelines state that consistent sender behavior and email volume contribute to positive sender reputation. Sudden, unexplained changes in template structure or content type can disrupt this pattern, affecting inbox placement.

20 Mar 2024 - Gmail Sender Guidelines

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