I am supporting a small stand-alone service for authors, who wish to share their texts with others, discuss them and so on.

As any service it requires sending lots of mails: activation (after join), confirmations and so on. I am using PHPMailer for that purpose.

**Question:** What additional steps should I take to prevent mails, sent by the service to be marked as SPAM? Should I adjust DNS settings somehow? Could I register my server with popular mail services somehow?

Any links as well as what comes from your experience are greatly appreciated.