The invention disclosed herein relates generally to mailpieces and more particularly, a hazardous material detector for detecting hazardous material in a mail stream. The present invention is directed, in general to detector for collecting sample(s) of hazardous materials from a mail processing device. The mailpiece generally comprises an envelope comprising a front side and a back side; holes formed in at least one of the front side or the back side of the envelope; a hazardous material test strip for detecting the presence of hazardous material in contact with the test strip; whereby when hazardous materials are detected by the hazardous material test strip a physical change occurs to the hazardous material test strip and the physical change can be viewed through at least one hole formed in the at least one of the front side or the back side of the envelope. The detector helps to quickly determine whether hazardous materials are present in the mail stream.