I've looked at the headers from a few emails (why can't I cut and paste the header info?) to see what is going on. The delayed emails from party A show "received from" rippling through 3 different Yahoo.com accounts in no time elapsed and then seem to be taking an hour plus a few seconds to be received at my mail server (secure.e-logbooks.com).
The emails from parties B and C pass from the originator to e-logbooks in one step, instantly, they come from bt.lon5 and asaout02 respectively. Not surprisingly, I am seeing the responses from parties B and C (with A's original included) before I see the original myself.
I would guess that the issue is with the final Yahoo server.........
Rans6andrew.