PMG does not support adding matches on the body through the rule system (there are quite a few threads in this forum where the rationale is explained in a bit more detail - but putting it shortly - it usually causes false positives and is...
* steht in der Regel auch online.mujtaba@gmail.com drinnen?
sonst wuerde ich mal sicherstellen, dass mails auch tatsaechlich am externen port von PMG angenommen werden (niemals public mails am internen port annehmen, das kann leicht dazu führen...
Mails fetched through PMG are passed through the Rule based filter system - just as mails received by PMG via SMTP - so your mails should be checked according to your rules already.
I hope this helps!