Does Using CiviMail for mailing lists on AWS violate the AWS Terms of Service?
"Probably, no."

This seems to be a legal question, and CiviCRM is a tool. CiviCRM provides a lot of support for not violating those terms ... but someone could still contrive ways to break the agreement, so as with any tool it's how you use it that really matters.

If a large number of spammers used a specific tool, you might see bans targeted against the tool itself. I don't think this is the case for CiviCRM.


  You will not distribute, publish, send, or facilitate the sending of unsolicited mass e-mail or other messages, promotions, advertising, or solicitations (like “spam”), including commercial advertising and informational announcements.


If your emails are solicited (opt-in) you should be OK here.


  You will not alter or obscure mail headers or assume a sender’s identity without the sender’s explicit permission.


CiviCRM should be OK here, provided you aren't pretending to be someone else.


  You will not collect replies to messages sent from another internet service provider if those messages violate this Policy or the acceptable use policy of that provider.


This applies the policy to inbound/return email also.