I think some of my emails are getting lost. For instance, of three to the same address, No1 failed, no2 succeeded, and no3 failed, in quick succession.
I don't always seem to get notifications of failure, but when I do, [email protected] is involved. I'm with Orange, formerly Wanadoo, formerly Freeserve.

I think there's some sort of blacklisting going on, but it's way above my head.

Any help at all will be greatly appreciated.