Question about ietf mailman

To: Working Group Chairs <wgchairs at ietf.org>
Subject: Question about ietf mailman
From: Cullen Jennings <fluffy at cisco.com>
Date: Fri, 1 May 2009 09:04:55 -0600
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I got a message that was held because

Reason: Message has implicit destination

What does this mean?

Follow-Ups:
- Re: Question about ietf mailman
  - From: Vijay K. Gurbani
- Re: Question about ietf mailman
  - From: James M Galvin
- Re: Question about ietf mailman
  - From: David Frascone