Mike wrote:

Or more likely not receiving them in the first place. Usenet is not a
perfect delivery system.

Agreed, Plusnet has had a few niggles at this end lately, I've never
known an ISP that doesn't from time to time ...

I don't think I see more than 75% of replies judging by replies I see to
posts I don't remember.

That's often google groups "forgetting" the references header, on
messages where someone has changed the subject as the thread develops :-(