Here's a final (hopefully) review of uptake for the openstack-discuss mailing list, now that the old lists it replaced have been closed for three months. See my previous reports[0][1] from the one- and two-month anniversaries. The volume of posts from non-subscribers landing in the moderation queue has continued to dwindle to only a few each week now. We've reached 934 subscribers to openstack-discuss (up from 830 in the previous report). 76% of the addresses used to send 10 or more messages to the old lists in 2018 are now subscribed to the new one (it was 75% a month ago so we're probably in the long tail now). As anticipated, posting volume rose in February to 1083 messages as compared to January's 958; for reference that's an 11% drop from the 1196 we had in Februafy 2018 (and again recall that right at 10% of the messages on the old lists were duplicates from cross-posting). We're continuing to investigate causes of messages through the list failing DKIM signature validation: * The most frequent cause was Mailman's recipient deduplication, since it works by filtering list subscribers out of the Cc header on receipt prior to processing for redelivery. As an experiment we've removed[2] it from Mailman's module pipeline, which has significantly reduced the number of invalid DKIM signatures (but at the expense of an increase in people receiving duplicate copies of list replies on which they were also Cc'd directly). * For the next most common cause, we've observed some mail servers using the much more strict "simple" header canonicalization algorithm[3] which makes whitespace in message headers significant (as opposed to the more popular "relaxed" canonicalization), and Mailman has a penchant for normalizing whitespace in message headers prior to forwarding which invalidates these particular signatures. We're not sure what the best option for addressing this is yet, but are considering reaching out to the affected individuals to see if they'll lobby their respective organizations to reconsider their choice of canonicalization. * The third and least common cause we've identified is a participant whose References header incorrectly adds a comma separator (RFC 822 parser spec[4] says space/tab/CRLF are the only allowed separators here), so when Mailman reformats the references list prior to forwarding it concatenates some elements. We don't have a great solution for this one either aside from asking the affected individual to work out whether the problem is being introduced by their MUA or their organization's MTA. [0] http://lists.openstack.org/pipermail/openstack-discuss/2019-January/001386.h... [1] http://lists.openstack.org/pipermail/openstack-discuss/2019-February/002335.... [2] https://review.openstack.org/635078 [3] http://dkim.org/specs/rfc4871-dkimbase.html#canonicalization [4] https://tools.ietf.org/html/rfc822#section-3.3 -- Jeremy Stanley