Kimmo L writes:
What does mailman conf -k anonymous_list_keep_headers show, and what is the content of mailman/handlers/cleanse.py?
Command output: [mailman] anonymous_list_keep_headers:
Mark may have more suggestions, but this is almost certainly the cause of the problem. The default for this parameter is
anonymous_list_keep_headers: ^(?!x-) ^x-mailman- ^x-content-filtered-by: ^x-topics: ^x-ack: ^x-beenthere: ^x-list-administrivia: ^x-spam-
which is a list of strings separated by spaces, and I believe the leading space on the second line is significant (meaning a continuation of the list on the first line).
There are a number of possibilities that cause this. (1) Check whether anonymous_list_keep_headers is set in mailman.cfg. If it is, it may be all you need to do is remove a spurious newline after the keyword anonymous_list_keep_headers. Otherwise, you can restore the default by copying the setting above. (2) If not, schema.cfg is corrupt or missing, and the default setting for anonymous_list_keep_headers is empty. In that case you should get a pristine copy of schema.cfg to compare to and check for any other undesired changes.
If you actually intended to change the value of this parameter, (1) you must keep the ^(?!x-) because this protects all the standard fields like To, From, Content-Type and Message-ID that are essential for any mail system; (2) you should keep the following: ^x-mailman- ^x-topics: ^x-ack: ^x-beenthere: ^x-list-administrivia: because they are used internally by Mailman, and do not contain any identifying information; (3) you probably should keep ^x-content-filtered-by: because it is used by Mailman, and should not contain identifying information; and (4) you may want to remove x-spam- because they occasionally identify MTAs upstream of you, but this degree of anonymization is rarely needed.
And content of mailman/handlers/cleanse.py:
This appears to be unchanged from the distribution, as expected.