Thanks for the clarification. I wasn't previously aware of the maximum dimension on the height. I was just going by what is said in the first message of the forum topic entitled "Subject: [Contributions] How you can submit pictures (NEW)", which states:

"In the case that the picture is ready to use (i.e. no borders & correct ratio) here are the limitations of the site: 720 pixels wide, and 80 KB."

Just a friendly suggestion, but maybe you might want to modify this message to add something about the 500 pixels maximum height just for possible future contributors' reference.