Thought to have originated on TOTSE this is a common reply to a very long post. It means Too long/Didn't read.
Person 1: Here is my thought on the meaning of life...(Goes on for another 1000 words
Person 2: tl/dr
Prices shown in USD.
邮件由 firstname.lastname@example.org 发出。我们决不会发送垃圾邮件。