What is an "implicit destination"

[perryh at pluto.rain.com]

I go this auto-response after replying to a message on questions@
a few hours ago:

> From: owner-freebsd-questions at freebsd.org
> Subject: Your message to freebsd-questions awaits moderator approval
> Date: Sun, 04 Mar 2007 05:43:56 +0000
>
> Your mail to 'freebsd-questions' with the subject
>
>     Re: BSDstats report for Mar 1st, 2006
>
> Is being held until the list moderator can review it for approval.
>
> The reason it is being held:
>
>     Message has implicit destination
>
> Either the message will get posted to the list, or you will receive
> notification of the moderator's decision.  If you would like to cancel
> this posting, please visit the following URL:
<snip>
> PLEASE NOTE!  If you would like to post freely to the list, please
> subscribe first.  If you post from multiple addresses, you can
> subscribe each address and go into the options page and select 'no
> mail' for all but one address. This will allow you to post without
> delay in the future.

but I *am* subscribed!