The problem is not so much bulk sending of mail, but sending of unwanted mail from one user to another. Amazon might shut you down if you have a large number of

The problem is not so much bulk sending of mail, but sending of unwanted mail from one user to another. Amazon might shut you down if you have a large number of recipients marking these unwanted messages as spam. Perhaps you should record enough information about sender (ip address, unique cookie) so that you can bulk delete and blacklist a problem sender. You can identify problem senders from the unsubscribe link that should be included in the messages.