Version:            (using KDE KDE 3.0.4)
Installed from:    SuSE RPMs
OS:          Linux

I sent an .vcf file with kmail as an attachment and changed the mime type from text/x-vcard to text/directory manually.
It was not possible to create the full correct Mime Type with kmail, since it did not allow me to type additional information (profile and charset) after the type itself.
So the attachment had
Content-Type: text/directory
instead of
Content-Type: text/x-vcard
resp.
Content-Type: text/directory; profile="vcard"; charset=...

When kmail received the mail with type text/directory, it neither detected the mime type itself as directory mime type nor did it snoop the file and detected, that it was a directory of profile vcard.
Instead it treated it like text/plain.

Examples on vCards and relating bugs:
Bug # 49801
Bug # 49802

Bye