Images
Signature images - company logos, campaign banners and profile photos - come from three sources in SignatureCat: the built-in image library, external URLs you host yourself, and Google Directory profile photos. This page is the reference; the practical guide is Banners and logos.
The image library
Each workspace has one library with two kinds of entries:
| Kind | Rendered size | Token | Library cap |
|---|---|---|---|
| Logo | 115x115 px | {{logo}} | 200 entries |
| Banner | 450x100 px, max-width 100% | {{banner}} | 200 entries |
Library entries carry an optional label and an optional click-through link. Each template selects its own logo and banner from the library; templates without a selection render a neutral placeholder. Uploads are PNG or JPG, up to 5 MB (200 KB recommended); SVG is not accepted.
Where images are served from
- Library uploads are stored by SignatureCat and served from
https://images.signature.cat/...over a CDN with long-lived caching. - With a verified custom image domain, newly rendered signatures serve library images from your subdomain (for example
images.yourcompany.com) instead - better deliverability, same storage. - External URL images ("I have a link") are hot-linked from wherever you host them. They must be public and HTTPS; ideally host them on your own domain.
Profile photos
The {{photo}} variable uses the user's Google profile photo from Directory (auto-scaled to 400 px). It is not part of the library - users and admins manage profile photos in Google Workspace. See Template variables.
Lifecycle notes
- Replacing an image: add the new file to the library and select it on the template - or keep the same library entry and only update its click-through link (picked up on the next render).
- Deleting a library entry detaches it from templates that use it (they fall back to the placeholder) after a warning with the usage count.
- Already-sent emails are never affected by library changes.
Deliverability tips
- Keep files small (banners under 200 KB) - large images slow rendering and hurt spam scores.
- Serve images from your own domain with a custom image domain - mail clients trust the sender's domain more.
- Gmail proxies images for recipients, so exotic hosting setups (IP allowlists, referer checks) will break rendering. Keep images plainly public.