Originally Posted by Eschaton

You need DKIM and SPF records -- not just a decent host. You also need to comply with CAN-SPAM standards (easy unsubscribe, address, etc). You can't just mail out to people and expect to hit their mailboxes. You also need throttling, bounce filtering, etc.

The problem I've found with adult sites is it's notoriously hard to hit mailboxes. Any adult mention and you're mailing is spammed. Now with GMail they also have new "Social" and "Promotions" tabs that automatically filter people's inbox -- so if you're trying to sell something that's where it'll go.

For reasonable size lists (over 10,000) I wouldn't expect better than a 10% open-rate. For smaller, customer based lists maybe more. If you send out 200 emails your open rate will probably be higher as if you're mailing over 1k emails per hour, providers might start rejecting your emails, if not already listing them as spam/junk.