From time to time we run into marketers who think that they have deliverability covered because they have signed up with an Email Service Provider (ESP). You've probably even seen some ESPs that are promoting their very high delivery rates. This is confusing and misleading, because the ESP fully controls only one of the five major drivers of deliverability failures.
Major consumer mailbox providers and business filtering applications look at five key data points to evaluate the trustworthiness of incoming messaging streams. They are:
1. Well-configured infrastructure: Since spammers typically send email from compromised machines on botnets, they don't have the access to properly configure these machines. Therefore, badly configured mail servers look spammy and will cause the mail coming from that server to be blocked. ESPs completely control their infrastructure and typically do a fantastic job at keeping them in good working order. Look for your ESP to authenticate your mail with DKIM, SPF and Sender ID. They should also be able to provide you with a reverse DNS address that does not look dynamic. And, they can and should be able to throttle email sends to conform to the ISPs thresholds for how much mail they are willing to accept in a certain period of time. But the absolute most important thing your ESP can do for you is put you on a dedicated IP address. Ask for it and be willing to pay a little extra for it. You don't want to inherit the reputation of those other mailers that are on your IP address.
2. Complaint rates: When one of our clients runs into a delivery problem, more often than not, it's high complaint rate that causes the problem. End users at the ISPs are hitting the "this is spam" button at a higher rate on their email. This causes their mail to get rejected by the reputation systems at the various ISPs. The ESP does not control the factors that drive complaints: proper notice and choice at the point of opt-in, relevance of offer, frequency of mailing and sourcing of data are all in the marketer's control. But your ESP can help you by making sure you are signed up for all available feedback loops and then processing those complaints as unsubscribes.
3. Unknown user rate: Spammers don't tend to clean their lists of bad addresses. When ISPs see a server sending a high number of emails to unknown users it looks spammy. To avoid looking like a spammer, don't have dead addresses on your list. Your ESP can help you, by implementing good bound processing that can tell reliably that a dead address is really dead and quickly removing it from your list. But you have control over keeping dead addresses from getting onto your list in the first place. Send a welcome message when someone signs up for your email. You can also implement list hygiene algorithms that prevent the addition of addresses that cannot be good (because they contain typos, or don't conform to the ISP naming convention, for example).
4. Spam traps: Spam traps, also called honey pots, are email addresses maintained by ISPs or blacklist operators to catch spammers. These email addresses have either never signed up for anything or they are extremely old addresses that have been dormant (and returned a hard bounce) for some length of time. Most ISPs have spam trap feeds of their own or use a filtering technology powered by spam traps or both. How do spam traps get on the lists of legitimate senders? They most often come from mailing to an old list, mailing extremely infrequently (thus hitting those very old addresses) or from using bad data sources. There is nothing your ESP can do to keep spam traps off your list.
5. Content: There are many systems that filter based on content. While content is a less common reason for messages not being delivered than reputation, it is a factor. Systems like Symantec Brightmail, Cloudmark and others are widely used by ISPs to fingerprint messages and determine the reputation of those fingerprints. ESPs clearly don't control the content of your messages.
Take charge, marketers! Deliverability is your responsibility. And the good news is that you have the skills to rise to this challenge. Good deliverability comes from good marketing. Maintain a good, clean list. If a data offer is too good to be true, beware. Send fun, valuable, relevant messages. And analyze deliverability metrics alongside response metrics so you can assess the true effectiveness of your efforts.