how could I transfer a custom IQ via openfire?

Hi guys:

when I send a custom IQ to someone, I got a

error code="503" type="cancel"><service-unavailable xmlns="urn:ietf:params:x....

from openfire. It is clear because openfire don't know how to handle it.

IQhandler of openfire will works I think.

but the only thing I want to do is just send an IQ packet to the target client so I can return result IQ from the client.

in other words, openfire do not need to handle it, just pass it will be fine.

so my question is : How could I prevent openfire from blocking my custom IQ without developing an IQhandler plugin?

or, did I get an misunderstanding of using IQ? or an plugin is a must have for this situation?

any kind answer or help is welcome!