Getting delivered is your biggest concern. If you end up in a bad IP range, or a large email site (ie its automated systems) figure you might be spam, people wo

Getting delivered is your biggest concern. If you end up in a bad IP range, or a large email site (ie its automated systems) figure you might be spam, people won't see your mail. This can be as simple as a minority of your email recipients hitting "Mark as Spam" in their webmail client to make your stuff go away. I've worked someplace where this was handled inhouse. You need to keep an eye on the various blacklisting systems out there, consider making sure you conform to the latest "emails that don't have this are probably spam" trends, and set up "feedback loops" with major mail providers like Hotmail and GMail. The purpose of the feedback loop is essentially to have your system automatically unsubscribe people who indicate that they don't want your mail any more, even if they do so with the "This is Spam" button instead of unsubscribing properly. I might need to send mail soon and I'm considering doing it with a provider like MailChimp (who have a poorly advertised API for sending individual mails, rather than bulk mails) or postmarkapp.com