Y. Yousend logo v1

https://brandon.works/yousend-v1-img

Originated from the MSN days where users would use emoticons by typing in letters/symbols and it would automatically turn into an emoticon.
"Y" was the default characters you had to type in for thumbs up, there were plenty of preset emoticons on MSN including (N) - thumbs down, :o - surprised face, :p - tongue out, (H) - cool face and many many more. Some, such as the (Y) - thumbs up emoticon had no connection to how the thumbs up looks compared to the characters you had to type in where as some, such as :o did (kind of) replicate a surprised face.