untrusted packages warning for mozilla.debian.net

[jidanni at jidanni.org]

Say can I remove aptitude's
"WARNING: untrusted versions of the following packages will be installed!"
Does mozilla.debian.net have a key? One cannot see what other files are on
that machine.

By the way, it's my very first bug: when one hits "release notes":
The requested URL /en-US/iceweasel/4.0b7/releasenotes/ was not found on this server.