One of the main (and probably most important) reasons email goes undelivered is because subscribers are complaining about your messages. Subscribers complain to their ISP by marking your email as spam and these complaints affect your email reputation. Each ISP has a threshold for complaints and if you cross it, your email gets blocked at the gateway.
There are a number of reasons why subscribers complain about your email, but in order to find out whom and why, you need to have access to feedback loop information. Complaint feedback loops capture subscriber complaints for the ISPs, but the information is available to email senders if they sign up to receive the data. With access to the data you can do three things: Read More ›