One common issue is that images do not appear correctly within the signature, although they may appear correctly in the 'Preview' panel. Instead of seeing the image you expect, a blue question mark or empty rectangle appears, e.g.:

These issues are caused by either the HTML code itself or the fact that the supplied image is not accessible over the internet (HTTPS-server recommended). We've outlined some tips below that can help you format your HTML to appropriately display images:

  • Use inline styles only (CSS blocks are not universally supported)
  • Use supported image types only (i.e., PNG, GIF, JPG, not SVG)
  • Use absolute image tags with HTTPS server-hosted images, e.g. 
<img src="">


  • Ensure that the linked images are not restricted for use via X-Frame-Options header.

If you'd like personalized assistance with your HTML code or image hosting, please contact us for paid support.