I have a URL with an apex:image tag like this:
<apex:image value="/img/icon/mail32.png" width="15px" height="15px" style="padding-right: 10px;padding-left: 10px;" />
I am trying to find the image's location but I am unable to find. I could not find this in documents, files or static resources. When I use the URL like : https://mysalesforceinstance/img/icon/mail32.png . I can see the image showing up. Where is this image located?