I don't try to dynamically link to images in signatures so I'm not familiar with the way this works. (I always embed the image into the signature.) But the way the report names the file "instagram.jpg" as a relative pathname, and without any protocol has me wondering if the message is just being economic, or if there is really a need for a full absolute pathname.

You say you can see the image is "still available on server". Which server? How do you view it to check? How did you create your signature, and how did you add this image to it?

Hi there.

Well pictures are on postimage.org, I can see them browsing the URL. TB just doesn't show path in popup messages, in the signature body the path is absolute. I moved the pictures to imgur.com and now it's working. Don't know what's changed, I changed nothing, the problem occours only with pictures from postimage.org in the signature, no problems with pictures from postimage.org in mail body.

Thanks.