When mailman sends a digest including 8-bit messages, it fails to add a Content-Transfer-Encoding header, and just sends 8-bit data with no indication that it's doing so. This violates RFC2045 and causes the mail to be rejected by some mail servers.
Created attachment 45680 [details] offending outgoing message.
O.K., I've done a bunch of testing on the current mailman version, 2.1.5 and as far as I can tell its handling this correctly (on the assumption it receives a correctly encoded email message). When a receipient is set to receive a mime digest the multipart components in the multipart/digest is getting the Content-Transfer-Encoding copied into it from the original email message. When set to plain digest the non-7bit chars are stripped out. When rfc 2047 encoded words appear in an email header the summary section reduces the encoded word to a "?" in 7bit ascii All seems to be well in FC1,FC2,FC3,FC4,RHEL3,RHEL4