I know that it must be done only unintentionally by PDML-ers that subscribe to the digest version, but posting to the PDML with subject lines with the "pentax-discuss-d Digest Vnn #nn" format (by replying to digest messages without fixing the subject line) is not very helpful.
I would assume that the sender usually wants his/her post be be read by anyone interested in whatever subject he/she is posting about. However, speaking entirely for myself, I don't have time to read all the PDML posts, so that I read only the messages with subject lines that interest me, and subject lines that say only "pentax-discuss-d Digest Vnn #nn" do not sound interesting and are ignored. So, I would suggest that, when any digest PDML-er mistakenly sends out a reply to some thread but sends it with a "pentax-discuss-d Digest Vnn #nn" title, that he/she re-title it and send it again. If the post has info worth sharing (and I'm assuming that is usually the case), then it is worth sending it again properly "labeled". Just some personal thoughts... I'm really trying to be helpful, and I'm not trying to be merely critical. Fred (in pseudo-curmudgeon mode)