We have an existing website, where users can signup with gmail/yahoo/hotmail etc, import their email contacts and invite their friends. Much like Facebook/LinkedIn etc. The website is experiencing exponential viral growth, and we need a server that can handle the amount of emails that we send out (currently around 300K mails/day, but growing). We're currently using mandrill, but its getting a bit expensive. We do receive some complaints from users, that didn't want the to receive the invite by their friends, and some of the emails in their contacts bounce. So we need multiple IP's plus a hosting provider, that's relaxed in this area... It could maybe be an offshore hosting company, where the regulations also is a bit relaxed. Can anyone recommend a hosting provider for this scenario?