I wonder if this might have something to do with ISPs beginning to implement SPF.
I doubt it. I have been having intermittent problems as well and something like SPF would tend to be all or nothing. I also don't use a commercial ISP for incoming mail and would probably know if the admins decided to implement something like SPF[especially since it would cause all my own mail to bounce]. My guess is that it is just load issues on the box running the lists[murphy?], it has happened before.[ie for some reason it only gets partially through sending to the list of people on the lists, sometimes it gets to my name, sometimes it doesn't, hence the intermittent problems. For people at the end of the list, it will tend to never get to their names.]
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