Update 2: Delivery to Mailman mailing lists is now up to date as of 3:00 pm. We will continue investigating the cause of the problem.
Update: Messages are gradually being delivered. Because newer messages are going out more quickly, they may be delivered out of order.
Messages to Mailman lists have been delayed since approximately 08:00 this morning. The problem is internal to Mailman; other mail is being delivered normally. Engineers are investigating the cause and resolution.