Inline Image vs Hosted Image in Email Signature

Images in email signatures are referenced one of three ways. Hosted images use an `<img src>` pointing to a URL on a CDN; the recipient's email client downloads the image on email open. Inline images use Content-ID references (`cid:`) with the image attached as a multipart part of the email message itself; the image renders without an external request but inflates the message size. Base64-encoded images embed the image binary directly in the HTML; same advantages and tradeoffs as inline. The choice depends on use case. Hosted is the most common because it keeps message size small, allows the image to be updated centrally (everyone sees the new logo when it changes), and is supported universally. The drawback is that image-blocking in Gmail and Outlook delays the visual signature until the recipient explicitly enables images. Inline/Content-ID guarantees the image renders without a separate request but adds 20-100KB per image to every message and prevents centralized image updates. Most signature management platforms use hosted images with a fast CDN, accepting the image-blocking trade-off.