As a punishment, prisoners could be prohibited from sending or receiving mail. This suspension of mail privileges could apply to individual prisoners, a whole block or – as was in the case in Dachau in 1933 – the entire camp. Individual groups of prisoners could also be excluded from postal correspondence; Jewish prisoners, for example, were not allowed to send or receive as much mail as political prisoners, and the so-called “Bible Students” (Jehovah’s Witnesses) were only allowed to correspond once every three months. Soviet prisoners of war were not allowed any mail in the concentration camps.