What the heck is a flushletter?

flush·let·ter

/flʌʃˈletər/

noun INFORMAL

a letter or email, typically from a potential employer, informing a candidate that they have not been selected for a position. The term humorously suggests that such letters, being of no practical value to the recipient, could be disposed of by "flushing" them away, akin to flushing away disappointment.

"The interview went well, but all I got was another flushletter in my inbox this morning."