[Mailman-Users] Tips in using a list addr for another lists's owner address?

I have a webmaster@lists.mydomain.com email list address that I use as the address of the owner of other lists at lists.mydomain.com.

This seems to work exactly as I intended (I can have a floating and/or group responsibility for the mydomain.com webmaster), except that I get a lot of messages like this sent to webmast@lists.mydomain.com:

From: mailman-bounces@lists.mydomain.com on Sun Jan 15 14:12:04 2006 Subject: svn-notify subscription notification Cause: Message has implicit destination

...presumably due to subscribe notices from the other email lists.

I haven't investigated this yet, but I thought I'd first ask this group: how can I eliminate/minimize these "Message has implicit destination" administrative notes?

-Matt