Outlook signature not showing images? Six causes and fixes

Few things look worse than a signature with a broken logo. Outlook is the most common place it happens, because there are four versions of it and each handles images slightly differently. Work through these causes in order.

1. The images are attached, not linked

If your signature was built by pasting images into Outlook’s signature editor, Outlook may embed them as attachments. Recipients then see a paperclip, or the image arrives as a separate file. Use a signature whose images are linked from a public HTTPS address instead.

2. The recipient blocks external images

Outlook blocks downloaded pictures by default for senders the recipient has not trusted. That is a privacy setting on their side. You cannot override it, but you can make sure the signature still makes sense without images: give every image short alt text, and keep your name and phone number as real text, never inside a picture.

3. The image address is not public or not HTTPS

Images stored on a company intranet, a shared drive or a site that needs a login will show for you and nobody else. Images served over plain http:// may be blocked. Host images on a public HTTPS address; Sendoff does this for you automatically.

4. The image has no width and height

Classic Outlook for Windows uses Word to render email. Without explicit width and height attributes, it may show an image at its full file size, which can push a small logo to fill the screen. Every image in a signature should have both attributes set.

5. The image is too large or in an unusual format

Stick to PNG or JPG, saved at twice the display size for sharpness on high-density screens, and keep each file small. SVG and WebP are not reliably supported in Outlook.

6. Rounded corners and backgrounds

Classic Outlook ignores CSS rounded corners, so circular headshots appear square, and background images are often dropped. This is expected behaviour. Choose a template that still looks right with square photos, or accept the difference in classic Outlook only.

Check your signature

Paste your signature HTML into the free Sendoff signature checker. It flags images without absolute URLs, missing alt text and missing widths, along with other problems that break signatures in Outlook.