Q 1. Can Super Admin of a WPMU network offers sub-site admin this e-newsletter plugin, and ask them all to use : Amazon Simple Email Service (Amazon SES)
Following post that said the plugin works with Amazon, but it doesn't say if it for both main site and sub-sites or just main site only.
Q2. If every sub site admin uses Amazon SES to send newsletter out, will the website hosting company (hosting the WPMU network) has a problem with it? Is this what you called "open relay"?
Q3. If all above is fine, could my WPMU network website be labeled as spam site assuming all sub-sites all use Amazon SES and a few "bad" sub site admin just act like spamming? (Once we offer it to sub site admins, you never know what people will do with it.)