what a difference a day makes ... errm a good night's sleep actually
re-reading the wiki document it finally dawned on me:
the zimbra_posixaccount.zip file should only contain the files (8) in the zimbra_posixaccount folder and nothing else.
Not as I thought yesterday: modify config_template.xml file and recreate the same zip file and structure as the downloaded file.
the reward: the zimlet is succesfully deployed.
away to the next stumbling block
