Comment 1 for bug 557493

This was fixed in Mailman 2.1.10 by adding the following to Defaults.py along with the code to implement it.

# Some list posts and mail to the -owner address may contain DomainKey or
# DomainKeys Identified Mail (DKIM) signature headers <http://www.dkim.org/>.
# Various list transformations to the message such as adding a list header or
# footer or scrubbing attachments or even reply-to munging can break these
# signatures. It is generally felt that these signatures have value, even if
# broken and even if the outgoing message is resigned. However, some sites
# may wish to remove these headers by setting this to Yes.
REMOVE_DKIM_HEADERS = No