IT Tips and Tricks

Problem:
Digests in Mailman are composed of a lots of unneeded headers which clutter the messages.

Solution:
Edit the Mailman configuration file manually as follows:
WARNING !!!: These headers are part of a the ‘RFC 1153’ which if changed can have unpredictable or unwanted effects.
So here I kept the headers: Date:, From:, Subject:, Keywords(if any), and Content-Type(quite important to keep)

Steps:
Rename the automatically compiled Python config file:
mv /usr/lib/mailman/Mailman/Defaults.pyc /usr/lib/mailman/Mailman/Defaults.pyc.orig

Edit the config file:
mcedit /usr/lib/mailman/Mailman/Defaults.py

and make the following changes from:

# Headers which should be kept in both RFC 1153 (plain) and MIME digests. RFC
# 1153 also specifies these headers in this exact order, so order matters.
MIME_DIGEST_KEEP_HEADERS = [
'Date', 'From', 'To', 'Cc', 'Subject', 'Message-ID', 'Keywords',
# I believe we should also keep these headers though.
'In-Reply-To', 'References', 'Content-Type', 'MIME-Version',
'Content-Transfer-Encoding', 'Precedence', 'Reply-To', 'List-Post',
# Mailman 2.0 adds these headers
'Message',
]
#
# The order in this list controls the order of the RFC 1153 digest headers.
# Also, any headers in this list will be kept in the MIME digest even if they
# don't appear in the MIME list above. Finally, headers appearing in both
# lists must be casewise the same or duplication can result in the digest.
PLAIN_DIGEST_KEEP_HEADERS = [
'Message',
# RFC 1153 headers in order
'Date', 'From', 'To', 'Cc', 'Subject', 'Message-ID', 'Keywords',
'Content-Type',
]

TO:

# Headers which should be kept in both RFC 1153 (plain) and MIME digests. RFC
# 1153 also specifies these headers in this exact order, so order matters.
#MIME_DIGEST_KEEP_HEADERS = [
# 'Date', 'From', 'To', 'Cc', 'Subject', 'Message-ID', 'Keywords',
# # I believe we should also keep these headers though.
# 'In-Reply-To', 'References', 'Content-Type', 'MIME-Version',
# 'Content-Transfer-Encoding', 'Precedence', 'Reply-To', 'List-Post',
# # Mailman 2.0 adds these headers
# 'Message',
# ]
#
MIME_DIGEST_KEEP_HEADERS = [
'Date', 'From', 'Subject', 'Keywords',
# I believe we should also keep these headers though.
'In-Reply-To', 'References', 'Content-Type', 'MIME-Version',
'Content-Transfer-Encoding', 'Precedence', 'Reply-To', 'List-Post',
]
#
# The order in this list controls the order of the RFC 1153 digest headers.
# Also, any headers in this list will be kept in the MIME digest even if they
# don't appear in the MIME list above. Finally, headers appearing in both
# lists must be casewise the same or duplication can result in the digest.
#PLAIN_DIGEST_KEEP_HEADERS = [
# 'Message',
# # RFC 1153 headers in order
# 'Date', 'From', 'To', 'Cc', 'Subject', 'Message-ID', 'Keywords',
# 'Content-Type',
# ]
#
PLAIN_DIGEST_KEEP_HEADERS = [
# RFC 1153 headers in order
'Date', 'From', 'Subject', 'Keywords',
'Content-Type',
]

Note: This might look confusing but just take a good look at the changes I made and you can see that I simply eliminated some headers from the 2 lists.
I simply kept the original version but commented it out as a reference in case things go wrong and I need to re-introduce some of them.