For multi-value attrs (like zimbraMailForwardingAddress) you have a number of options:
- by default it replaces all of them. So calling ModifyAccount with:
will replace all existing values of zimbraMailForwardingAddress with the ones specified.
- you can explcitly and/remove a single value using a +/- in front of the attr name:
that will remove the "v1" value, and add a "v2" value. Any other values for that attribute will be left unchanged. If you use +/- in front of an attr name, you must you it in front of all values for that attr name in the same call.
- you can remove all values by setting a single instance to the value to "":
since "" means unset, and you haven't specified a +/-, it will delete all existing values.
For a while we only supported the first first and last forms, which is definitely a pain when you have a multi-valued attribute with a lot of values. Instead of making the protocol more complex, we decided to just add the +/- syntax in front of the attr name so it worked immediately with existing SOAP calls and also via "zmprov" and all the internal provisioning APIs.