Checking for unique mail adresses

Hello,

I've got a problem with a quite chaotic XML file (generated from 
several thousands of mails :-P )

I managed to create a new XML file from it containing, among others, 
<mail> elements containing all the given mail adresses in those 
mails. This worked fine.

But now I need to know which ones are unique, i.e. sort out the 
double ones. Not just that, problem is, there might be other text in 
a <mail> element, like the user's name. I think it'd be possible to 
search for "words" (i.e. text parts before and after which comes a 
space) containing the @ symbol to filter out only the mails itself, 
but then I also still need to know only the unique ones.

How do I do it best? Am I on the right track, at least?

Thanks and bye,

Heiner

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