In the beginning of the 1970s most of the work of Department M was performed by hand. This labor included sorting and selecting suspicious mail, manually steaming it open, examining the contents, transcribing, copying or photographing the interior or exterior of the letter, in some cases, examining the letter for conspiratorial or stealth writing, resealing the envelope, and placing the letter back into circulation at Deutsche Post. As the secret operations heightened the suspicions during the Cold War, and with the postal service increasingly relied upon for cross-border communications thanks to the Berlin Wall preventing face to face meetings, Department M received more pressure to increase their efficiency through mechanical means.
One such machine used by the Stasi was referred to as the “PiD Trap.” This electronic device automatically scanned and screened regular letters from printed materials like newspaper excerpts, church letters, and advertisements. Like the organizational systems the Stasi employed, this apparatus made it possible to divide and focus the labor of their workers and expedited the sorting and determination of suspicious mail and “negative” or “hostile” influences from the west in the form of Politisch-ideologische Diversion (PiD). (Labrenz-Weiß, 28)
- Hanna Labrenz-Weiß, Abteilung M (MfS Handbuch). Hg. BStU. Berlin 2005.