[ChrisMAg2]

Amtmann Albrecht was the civil servant (clerk or officer), who signed the incoming/ recieving of this letter at "Luftwaffenpersonalamt".
It is "Geheim"(Secret), because natualy all information on military personel are regarded secret. Especialy because you could be also able to extract other information (the unit, their base, procedures [->this is arecommendation letter using the help of somebody in a higher position [somebody being represented by Generalstab des Luftwaffenkommando 4] then just the OIC of Lt. D. Rohwer at JG3] etc.) from this letter.