Release candidate 3 for Mailman 2.1.6 is now available. This fixes a late-breaking problem with RFC 2231 encoded headers containing bogus or non-existent charsets. Specifically, this release includes an updated version of the email package (2.5.6).
Please try this version out as much as possible. Hopefully Tokio and I will get a 2.1.6 final out in about two weeks.