The origin of the name is from the village Schleeßel. A small village not far from Groß Meckelsen, Klein Meckelsen, Zeven, Godenstedt, Selsingen located between the rivers Elbe and Weser. The first part of name “Schlee” is the bush sloe. second part “Sel” or “ßel” means in old German colony (human Settlement). The meaning is therefore the colony within a veldt of sloe. In Jordebuch from 1694 village was named Schlesel, later Schlesell, Schleßell and now Schleeßel. The increasing internationalization of the name is now often written as Schleessel.
The first Schleßelmann probably got the name because he moved from Schleeßel to somewhere else like Sittensen, Zeven, Godenstedt, or some other village. He was therefore the "Schleeßelmann" (Man fom Schleeßel). Or in other words, the man who came from the village in the middle of the veldt of sloe (or blackthorn , a sort of wild plumb).
From the University of Leipzig is a certificate of conformity about the name. It is published on schlesselmann.myheritage.com . In Schlesselmann family site click on Family Pictures (Familienfotos) and than then open the folder "Familiengutachten". There you will find Foto copies of this certificate. The meaning of Schleeßel itselfs is a bush called sloe (German “Schlehe”) or in English Blackthorn hedge. This is the historical tradition and therefore the crest of Reeßum contains a blossom of a sloe. Scheeßel is a part of the community Reeßum. Conspicuous is, that the letter ‘ß’ appears very often in different designations (Schleeßel, Scheeßel, Reeßum or even Schleßelmann). This has maybe to do with the old language (Lower German "Plattdeutsch") that some people still speak until today in this part of Germany.
Manfred Schleßelmann, Harsefeld & P.C.Schlesselman, Wichita