I'm trying to locate the images that are used for testing table cell containers and email layouts with images that was shared among the Litmus Community.

I forgot what the link was called, but it started off with a "p", and it has (from memory) the following syntax:

https://[p somthing]/640x480.png

And then when you share the email code to everyone in this forum, everyone can see what the emails are going to be when they just copy/paste and view it locally on the computer, hassle-free.

I would like to know what test image links they are, and which ones are more friendly towards the Litmus Community for their usage?

Or, as an alternative, I can just upload my own test images to Imgur, and use Imgur for sharing the email codes here in this forum.