Hope that somebody around here can look at this.
mx3.redhat.com is broken.
fedora-list@redhat.com: mx3.redhat.com [66.187.233.32]:
DATA
<<< 451 4.3.0 Problem running virus-scanner
It's rejecting all mail now. mx3.redhat.com is the primary MX for @redhat.com. Not all mail servers will retry other MXs, if DATA gets deferred at the primary; this is considered spammish behavior in some circles. Some mail servers do retry the backup MXs, which is why there's some trickle of list traffic now, but I suspect that ~90% of list messages are currently bottled up at the senders' mail relays.
And I was wondering why my list messages sent earlier today haven't shown up. Now I know (after taking corrective measures…)