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dead letter box

British  

noun

  1. a place where messages and other material can be left and collected secretly without the sender and the recipient meeting

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Example Sentences

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Even if Margolis had followed OPR's recommendation, the cases would almost certainly have wound up in the dead letter box.

From Slate • Feb. 22, 2010