[sork] passwd + vpopmail with disable_many_domains not changing password

[info at centralmail.de]

Hi,
this is my first post to the list.
I have a vpopmail install (compiled with disable_many_domains) which has 
one table for every domain (format: my_new_domain_tld) and has no 
pw_domain field by default..
Futher installed is latest horde and latest passwd (3)
I have been seeking the web the last days to get the password changing 
feature working - no success, could not find any hint so far...
Any hint how to proceed is really welcome
Thank you in advance
Claus