On 4/3/21 1:59 AM, Stephen J. Turnbull wrote:
Note that in those cases where the provider sends examples of "problematic" mail from your server but redacts customer identification, there are ways to "fingerprint" the message which the providers usually don't touch. Basically, add a header field with a hashed email address. Of course this requires message-per-subscriber which may be costly, and won't do much good unless you see enough of these to make it worth doing this as a policy matter.
Since this involves patching Mailman anyway, you can add code so this only happens for specific problematic domains. It's reported to be effective with AOL and (IIRC) Yahoo!
This is a feature in MM 2.1. From Defaults.py
# If the following is set to a non-empty string, that string is the name of a # header that will be added to personalized and VERPed deliveries with value # equal to the base64 encoding of the recipient's email address. This is # intended to enable identification of the recipient otherwise redacted from # "spam report" feedback loop messages. For example, if # RCPT_BASE64_HEADER_NAME = 'X-Mailman-R-Data' # a header like # X-Mailman-R-Data: dXNlckBleGFtcGxlLmNvbQo= # will be added to messages sent to user@@example.com. RCPT_BASE64_HEADER_NAME = ''
This feature doesn't yet exist in Mailman 3.
FWIW, Yahoo/AOL are not currently redacting the recipient address, but it may not be the address the message was sent to if intermediate forwarding is involved. Also, Hotmail is not currently redacting the recipient address. Personalizing deliveries and putting the recipient address in the msg_footer seems to work well for non-digest messages.