[Mailman-Users] attached "text.sxw" becomes "text.bin" in archives and digests, why?

[Robert Breithuber]

everytime an attachment becomes scrubbed, some document types get a new 
fileextension like .bin or .exe

e.g. the attached file was text.sxw (staroffice-text-document):

in archive and digests it gets scrubbed like this:

Dateiname   : plan.sxw
Dateityp    : application/vnd.sun.xml.writer
Dateigröße  : 5449 bytes
Beschreibung: nicht verfügbar
URL         : https://.../pipermail/.../attachments/.../plan.bin

why .bin? 

is this because the "scrubber" doesnt know what 
"application/vnd.sun.xml.writer" is ? 
why is the extension changed anyway?
can i affect this behavior in any way?

please help!

greetings,

robert

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