I do reliably get emails when it's my turn to move, but am not notified when my opponent has resigned. I've searched in vain for a setting. Am I missing something?

The system currenlty does not send emails on completion of a game. The only exception is when a game is deleted, which isn't really a completion... :-)

This is something I could add in future.

Regards

Thanks; I do think it's important to know. Otherwise, we're just left wondering why the opponent hasn't moved.

If you log into your 'My Games' page, which is where all your games are, you will see which games are current and which have been completed. You will also see how the games are progressing time wise. Also, your ratings will alter if your opponent resigns. Emails are only if you seldom log on. But if you have several games going, you'll need to check their progress anyway. Stoney has arranged this site in such a way that, as Woodpusher so succintly put it, 'We've got everything we need and nothing we don't'.