I subscribe to both lists. From examining the mail headers, here is a mail filtering algorithm that seems to deal with duplicate posts showing up from the other group. Create a cctalk and cctech saved mail folder in this order: put msgs with "To" header of either cctalk or classiccmp into cctalk put msgs with "To" header of cctech into cctech if "To" == cctalk and "Reply-To" == cctech, delete the message if "To" == cctech and "Reply-To" == cctalk, delete the message there are a couple stragglers for the case where "To" == classiccmp but this got the bulk of the dups.