Appropriate to thank examiners? I have just completed a research degree. By the rules of my university, my dissertation was examined by two outside examiners, whose identities were kept secret from me during the examination process. Now that I have received my results, my supervisor has told me who the examiners were (this was permitted by university rules and the consent of the examiners).

Is it appropriate to send them each an email thanking them for their efforts?
Yes. 

It's a lot of work to examine a thesis and (generally) this is unpaid work done in our own free-time. So a simple thank you will make your examiners feel appreciated. This will have the side benefit that your examiners will remember you in a positive light, which may be useful in the future when you are looking for a job, for a reference, for a place to visit to give a research talk, etc.

It never hurts to be polite.