Why should images always include dimensions?

Specifying width and height attributes in image tags reserves space in the layout before images load. Without dimensions, the email jumps and reflows as each image loads-creating a jarring user experience called "layout shift."

Technical benefits: Prevents layout reflow-the email renders correctly from the start. Maintains structure with images blocked-placeholder boxes preserve layout. Ensures proper scaling-especially important for retina images displayed smaller than actual size. Improves rendering speed-the client doesn't need to calculate sizes.

Always specify both width and height. Example: <img src="..." width="600" height="400" alt="...">. This small addition makes emails feel more professional and polished. The alternative-content jumping around as images load-feels amateurish and frustrates recipients.