STAMFORD—  Cenveo the largest manufacture of envelopes in North America has filed for Chapter 11.The 99 year old company at one time know as Mail Well has about 40 plants in the US. With sales of  about $1.5 billion , debt of $1.4 and only assets go $790 million it was running out of cash. Envelopes made up 47% of their sales the rest was labels, commercial printing and publisher services. They had about 50 plants in the US and 5,200 employees. They blame the shift by marketers from the mailbox to the internet. They are in the process of restructuring their debt. The bought National Envelope the previous largest envelope manufacture when it went under in 2000.