It's more than cross-mailings. I've been getting duplicates of some mail (but not all mail). Since I'm downstream of some rather congested nodes running software I don't fully trust, I just attributed it to delayed duplicates sent by the networking software to make sure one copy got by. But June's off in a different direction, so apparently that's not the answer. In some cases, the duplicates have been delayed by days or more, but they're clearly the same note. Nick