I'm wrestling with the best way to create some C# code to find all of
the unique email id strings I receive within an array.  Basically I
want to efficiently eliminate all of the duplicates.  Typically there
will be between 1 and a few hundred unique email ids, and worse case
it might be 20,000 to 50,000 unique email ids.

My first pass was to use a C# hashtable.  I use the hashtable to tell
me whether or not I've already seen the  email id string in the
array.  I don't care about the ordering of the email ids, all I care
about is finding all of the unique email ids.

Does anyone have any suggestion for a better solution?

Are there are gotchas for using a C# hashtable for this solution?