Let FreeRADIUS ignore a request from rlm_perl

Hey there, I'm using FreeRADIUS Version 2.2.8 and am wondering whether it is possible to ignore a request (i.e. send no reply at all) inside a rlm_perl module. I tried returning either RLM_MODULE_NOOP, RLM_MODULE_INVALID, RLM_MODULE_FAIL, and RLM_MODULE_HANDLED (without setting any reply attributes) inside an authenticate function. Although, in the end, they all result in the server rejecting the request, which is not what I want. How can I achieve this? -- Harm