Does Yahoo Mail cache BIMI images, and how do they handle image loading?

Yahoo Mail fully supports BIMI, fetching the brand's SVG logo directly from the URL specified in your BIMI DNS record. While early anecdotal reports suggested a lack of caching, the prevailing expert and industry view indicates that Yahoo, like other major providers, does cache these SVG images on its servers. This server-side caching helps improve performance and ensures consistent display for subsequent emails, rather than re-fetching the image every time. Yahoo also ensures control over image delivery by fetching logos directly from the sender's domain, rather than relying on CDNs, and may consider sender reputation for BIMI display.

Extending our understanding of Yahoo Mail's BIMI implementation, its approach to image caching and loading is quite specific. While early anecdotal reports suggested BIMI images were not cached, the prevailing expert and industry consensus now indicates that Yahoo Mail, like other major providers, does indeed cache these SVG assets. This caching is primarily for performance optimization, ensuring faster display of brand logos within inboxes and reducing repeated fetches. The Time-to-Live (TTL) value set for the BIMI DNS record can influence how long Yahoo caches the logo, though some companies might use overly low TTLs for static records. Furthermore, Yahoo's system exhibits a nuanced handling of BIMI images, determining eligibility based on factors like sender reputation and sometimes appearing to 'merge' or associate logos across related subdomains, leading to a consistent brand presence even on older emails.

Yahoo Mail does cache BIMI images, and this caching is likely in place to prevent their use as a tracking mechanism. Furthermore, Yahoo has a specific policy for handling BIMI image loading: as of late 2023, it requires logos to be hosted directly on the sender's domain, not on a Content Delivery Network (CDN). This direct fetching ensures Yahoo maintains control over the image delivery process, bypassing potential issues related to external CDN configurations or caching, and aiming for consistent, accurate display of the brand logo.

Building on prior insights, Yahoo Mail's handling of BIMI images consistently involves direct fetching of the SVG logo from the designated HTTPS URL, adhering to specific SVG format requirements. Although Yahoo's public documentation does not explicitly detail caching, a consensus across industry best practices, the M3AAWG guidelines, and implementations by other major email providers like Gmail, strongly indicates that Yahoo Mail indeed caches these verified brand images. This caching mechanism is crucial for optimizing display performance, reducing redundant fetches, and ensuring rapid, consistent presentation of brand logos across user inboxes. The process emphasizes fetching by Yahoo's internal systems, with specific requirements for the SVG format itself.