Spam from amazonaws.com

I have most spam pretty well blocked, but one source that does manage to 
get through is amazonaws.com.  I’ve been thinking of blocking it, but I 
occasionally order stuff from amazon.com and don’t want to cause a problem.

spamcop.net says that amazonaws.com refuses to accept their reports; of 
course, I’m not convinced that spamcop.net does any good anyway.  Any 
suggestions?  Cheers,
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Gib Henry