Images in emails can significantly impact deliverability, potentially causing them to land in spam folders. Multiple factors contribute, including the image's hosting domain reputation, the text within the image, excessive image size, a high image-to-text ratio, missing or irrelevant alt text, broken images, improper embedding or linking methods, poorly implemented CID images, use of tracking pixels, and rendering issues. Machine learning filters evaluate everything in the email, making proper formatting, optimization, and mindful implementation essential to avoid triggering spam filters and maintain a positive sender reputation.
11 marketer opinions
Images in emails can significantly impact deliverability and potentially cause emails to land in spam folders. Factors contributing to this include large image sizes, poor image hosting reputation, high image-to-text ratio, missing or irrelevant alt text, broken images, and the use of tracking pixels. Even rendering issues with background images and improper implementation of CID images can raise red flags with spam filters. Ultimately, it is important to carefully optimize images to avoid negatively affecting sender reputation and user experience.
Marketer view
Email marketer from StackOverflow warns that using CID (Content-ID) images, especially if improperly implemented, can be flagged as suspicious and lead to deliverability problems.
14 Nov 2024 - StackOverflow
Marketer view
Email marketer from Email Geeks shares that the text on an image can impact spam filters by changing image attributes.
22 Feb 2022 - Email Geeks
6 expert opinions
Images in emails can contribute to emails landing in spam. Factors include hosting images on domains with poor reputations, using excessively large images without optimization, failing to provide descriptive alt tags, and linking directly to images instead of embedding them. Email content is evaluated by machine learning filters and improperly implemented elements could affect deliverability.
Expert view
Expert from Word to the Wise shares that linking directly to images hosted on a server, rather than embedding them in the email, can be problematic. Many email clients block external image loading by default, and depending on how it's implemented it could raise deliverability flags.
2 Jan 2025 - Word to the Wise
Expert view
Expert from Email Geeks explains that anything in the email is evaluated by machine learning (ML) filters.
19 Oct 2021 - Email Geeks
3 technical articles
Email servers scrutinize the structure and content of emails, including how images are embedded. Improperly formatted images can lead to parsing errors and spam classification. Using images in a way that triggers spam filters can contribute to exceeding spam rate thresholds, negatively impacting deliverability. Content filters analyze images, and their properties contribute to the overall spam score.
Technical article
Documentation from Google explains that exceeding spam rate thresholds can negatively impact deliverability. Using images in a way that triggers spam filters contributes to the overall spam rate.
4 Oct 2024 - Google
Technical article
Documentation from Microsoft explains that their Smart Network Data Services (SNDS) uses content filters to identify potentially unwanted emails, and images are a part of this analysis. The properties of the images can contribute to the overall spam score.
20 Oct 2024 - Microsoft
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