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Will nearly 100 percent of my marketing email end up in my customers' spam folders?

The answer may be "yes" if your company doesn't change its email practices.

Fewer consumers are willing to spend right now, while most companies are anxious to improve their revenue numbers. If customers aren't buying enough, the solution may seem simple—send more email. Alas, customers who are not eager to buy are unlikely to be receptive to additional emails from you.

Instead of being financially rewarded for emailing more, you may be punished by a slackened or even negative response, and you might find that your revenue plummets while your email languishes in spam filters.

How can you determine how your email is performing?

Don't fixate on a single metric

There are many sides to the performance puzzle. For example, bounce-backs can't give a complete picture of your delivery success. You should also watch the number of delayed deliveries, sometimes known as soft bounces; these are emails that didn't make it through on the first delivery attempt.

Also, pay attention to your opt-out rates. The expected rate may depend on the kind of customers you have, but anything above one percent may indicate dissatisfied recipients. Less than half a percent is preferable, and less than a quarter of a percent should be achievable. Look at how your opt-out rate is trending: Even if your rate is low, a steady increase may signal a change in how your recipients perceive the value of your mail.

Timing is another factor. How long after your email goes out are you still getting clicks, views, and opt-outs? Knowing this information may help you estimate how long your email stays in people's inboxes and how far ahead you must plan in order to reach the largest audience.

Finally, keep in mind that email can drive response in other channels. Your Web site analytics should show traffic spikes correlated with your email campaigns. If you can track sales at your brick-and-mortar stores, you may see an increase in foot traffic as well.

Use all the tools you have

Most ESPs and email software can link email to Web analytics so that you can see what email readers do once they get to your Web site. Are readers responding to the offer you put in the email, or are they more interested in other things? Getting the right offer into the email itself will increase engagement.

Run deliverability reports if your email vendor offers them, to determine what proportion of your email passes common delivery filters and what proportion reaches user inboxes at ISPs rather than junk folders. Formatting, content, and historical user response are factors that determine those rates. Such a report may also give insight into how long it typically takes a message to travel from your sending servers to the customers' mailboxes.

It's also important to pay attention to what your email looks like to recipients. Users are more likely to opt out when messages look bad. Worse, they might hit the "report spam" button and affect your ability to reach others at the same ISP. Use preview tools if your vendor or software offers them; otherwise, set up free accounts at Yahoo, Hotmail, or Gmail to view emails as your customers see them.

Conduct recency, frequency, and monetary value (RFM) analysis of your email campaigns to understand the level of engagement of your customers. Customers who are not as engaged are more likely to opt out or simply tag you as a spammer, which will cause your deliverability to suffer, especially in a market where fewer people want to be engaged and more companies are desperate for added revenue.

What's important to get email through delivery obstacles?

ISP mail filtering is intentionally inscrutable

Many ISPs live in fear that providing clues as to how their filters distinguish well-behaved email will allow spammers to exploit that knowledge. The filtering rules vary from one ISP to the next, and they change constantly to adapt to new tricks by spammers.

ISPs experiment with strategies that may have side-effects they didn't predict, so a message that reached the inbox today may not tomorrow. In the end, good sender behavior and customer loyalty are your best defenses.

Within the past couple years, ISP strategies have shifted away from outright blocking to traffic control. "Greylisting" is a deliberate soft-bounce delay to force the sender to retry delivery at least once; it's "grey" because it's not quite a blacklist, but it penalizes unknown or suspect senders. Another practice that is frequently used is rate limiting, which is where only a certain number of emails per connection or per hour are accepted.

B2B mail faces different challenges

If your customers are other businesses rather than consumers, the hurdles are often higher. Corporate mail servers are also more likely to require rigid compliance with technical best-practices, which may include the following:

  • A working address for replies (you should avoid labor-saving shortcuts like a return address of "noreply@yourdomain")
  • Well-formatted message bodies conforming to standards
  • Accurate domain name service (DNS) entries for the servers that send your mail and the servers that accept replies
  • No SMTP transaction mistakes

Your ESP or email marketing software should provide compliance with these technical practices, but if you want details on these technical specifications, a good resource is

What can you do to improve?

Consider it your privilege, not your right, to send email

Space out your mailings. The right frequency depends on your customer base. Email to different sub-lists to mail more frequently, but don't take a shortcut by resending the same message, because duplication may look like spam to an ISP.

Be selective about who gets more frequent mail. Most likely, it will be better to remail people who do respond rather than people who do not. Of course, this depends on the purpose of your message; for example, you don't need to re-invite someone who has already signed up for your webinar.

RFM analysis is one approach to segment your customers by engagement and track changes in behavior.

Plan ahead

If you're announcing a specific event, send the email early, not at the last minute. You should expect rate-limiting and network factors to prevent high-speed delivery on occasion. If you must mail at the last minute, remember that some customers won't see your email until it's too late.

Even if your mailing is not time-sensitive, be considerate of the ISPs, which act as gatekeepers for your customers. Allow time for deferred deliveries to clear before you begin another mailing to an overlapping list of addresses.

Look forward, not back

The Web is a fast-moving environment, and what has been working for you for years may no longer be your best approach. So don't lump your most valuable customers in with everyone else on every mailing.

Also, change your offer when attempting to re-engage non-responders, and offer recipients something that they will value, not just the latest thing that you need to move off your shelves

Stay engaged with your email service or software provider

Your provider should be prepared to work with you to keep up with best-practices. Don't just treat them like a print shop or a postage meter. A good provider can help you head off problems before they become crises, but only if you are willing to stay involved.


Your deliverability ratings are just as important to your company as your credit score is to you. Understand it, nurture it, and safeguard it, because revenue and customer loyalty depend on it.

Practices that sound good around your company's conference table may lower your email deliverability, which will only undermine your company in the long run.

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Barton Schaefer, PhD is CTO of iPost (