If you have the cleartext password, then you could use the zmprov program to create accounts and/or set the password if it changes.
to create accounts:
Code:
/opt/zimbra/bin/zmprov ca account@your.domain thepassword [other attrs]
to set the password on an existing account:
Code:
/opt/zimbra/bin/zmprov sp account@your.domain thepassword
roland