This appears to be a fairly common problem; I suspect that MailMan is using a header to set the date and some folks have their client set to preposterous dates. See:

http://www.omnigroup.com/mailman/archive/webobjects-dev/

The above is from a mailing list managed with 2.0b3.

b.bum

On Monday, April 30, 2001, at 12:02 PM, mailman-developers- request@python.org wrote:

Date: Sun, 29 Apr 2001 19:12:29 +0000 (GMT) From: Ousmane Wilane <wilane@MINT.SN> To: <mailman-developers@python.org> Subject: [Mailman-Developers] 2006 archives already online!

Hi, Take a look at the Mailman-dev archives page, we have a 2006-April line there with only one message. Perhaps I'm missing sth! Kind regars.

W. O.