I'm kind of surprised that you see it going to itself, but AWS does have lots of restrictions on port 25. Have you gone through the process to get it unblocked?
While it is possible to run your own mail server on EC2 if you go through the process, generally it's a lot easier to use SES (or a competitor's mail sending service) if all you're doing is sending emails out and don't need a full mail server.
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