Deliverability is a commonly discussed topic among digital marketers, and for good reason! It’s the lifeblood of many businesses and unfortunately it remains a complete mystery to many of them. Fortunately it’s also something that you have quite a bit of control over.

It’s a common misconception that all email marketing platforms have similar deliverability. I’ve often heard marketers say if you have delivery issues you should figure out what you’re doing wrong instead of jumping ship for a new shiny platform. I appreciate the sentiment, but for the budding entrepreneur this is destructive advice. If you don’t have a solid reference point, how do you know if there’s room for improvement in the first place?

Deliverability is 99% about you and your content.

But that last 1% can stop you in your tracks.

Let’s get this out of the way first. If you’re trying to cut corners or are failing to do some basic email marketing housekeeping you’re going to have a bad time. Here’s a really brief list of things that will land you on the wrong side of the spam filter:

  • Buying email lists. If you’re sending emails to people who didn’t explicitly opt-in to receive them you’re going to get some high complaint rates. Just don’t do it.
  • Going long periods without emailing your list. Emailing a cold list yields poor results. Set up an automated nurture sequence and make sure you keep up with new content. Recycling newsletters back into your nurture sequence is a great way to build content over time.
  • Sending from a domain you don’t own. If you’re sending from a Gmail or Yahoo! address deliverability will be poor. Use your own domain, and make sure you follow your email platform’s instructions to configure your DNS records.
  • Making unsubscribing difficult. If someone can’t figure out how to unsubscribe they’re going to just report you as spam.

“Email” is just a set of agreed-upon standards

We think of email as a singular thing, but in reality it’s a set of standards that many, many different organizations and individuals have written to define the nuances of how messages should be formatted and how they are sent from server to server.

Email has become an incredibly complex technology. It’s a multi-layered beast of a process to get a simple message from me to you. To simplify what’s happening, there’s two primary layers of checks and balances that happen when an email server receives a message: (1) authorizing that the email came from a “trusted” source, and (2) using some intelligent screening to guess if it’s a message you actually want to read.

In order for this process to work we’ve developed some common standards that ensure Yahoo! knows how to verify an email sent by Google, for example. But those standards are really complex, too. The degree to which everyone in the industry has adopted unified standards has a pretty wide range, and if your email marketing platform misses a step or allows their technology to fall behind the result is a drop in that confidence level email servers compute when they receive your message.

Before you work on anything else, ensure your email identity is rock-solid.

There are 3 technologies you need to know about that work together to verify the identity of the message sender: SPF, DKIM, and DMARC.

SPF (Sender Policy Framework)

SPF records allow receiving email servers to check if the server that sent the message is on the list of approved senders. You set this list by creating a TXT record on your domain that lists which servers are allowed to send mail for your domain.

Sidenote: some DNS hosting platforms support a separate record type specifically for SPF records, these are not TXT records but a specific SPF type. Do not use these records as the majority of email service provider deployments don’t actually look at this record type.

Let’s look at a typical SPF entry. This is the TXT entry I have for my domain:

v=spf1 ~all

You can see I’m allowing messages to be sent from servers that can be discovered using the and domains. The “~all” is the catch-all for any message that isn’t sent from one of the listed domains, and the “~” prefix tells servers to mark it as a message that should fail, you can also use a “-” to indicate these messages should fail outright instead of just being marked differently.

The SPF Specification defines a limit of 10 on the number of lookups servers can perform when validating a message, but the thing to keep in mind is a single domain entry may result in multiple IP lookups. That entry is actually 3 lookups (at the time of writing), so it’s a good idea to limit the number of domains you specify here—and thus the number of services you send email from—to 2 or 3.

DKIM (DomainKeys Identified Mail)

DKIM is a pretty complex technology, so I’ll try to keep this brief. What DKIM allows you to do is digitally sign your emails with a unique signature. When email servers receive your message, they can check to see if the message was signed with your signature, and if not, they know it wasn’t really from you. You absolutely need to set this up. If you haven’t done this you’ll end up in spam folders more often than you’d like, and when your messages do get through many email clients like Gmail will display a warning to users that looks like this:

It’s subtle, but over time they’ll make this more prominent to encourage more email senders to adopt DKIM.

The adoption of DKIM has not only been slow, but many email platforms only have partial implementations.

DKIM can come in two primary flavors. Your email platform itself can sign all messages (including other senders on the same platform) using their own key, or they can sign messages using your own custom key. Using a custom key is better in all respects. It’s another layer of validation that messages are coming from you, the owner of the domain, and not an imposter.

Some email marketing platforms, most notably Infusionsoft, do not support using your own DKIM key and instead sign all messages using their own key. This is not treated as favorably as domain-specific keys when validating a message sender so, ceteris paribus, another platform that supports custom DKIM keys would yield better results.

DMARC (Domain-based Message Authentication, Reporting and Conformance)

DMARC simply sets up a policy that tells email servers how to handle messages that pass or fail the SPF and DKIM validation. It also allows you to specify an email address to send pass/fail reports to, which will help you identify if and why your messages are being rejected so you can resolve the problems. The reports get pretty technical, so I recommend using the free DMARC digest tool from Postmark. Review the weekly digests and over time you can correct things that are causing your messages to get rejected.

Email Sender Reputation

When your email server receives a message they do some pretty complex analysis to try to figure out if it’s a message that you will actually want to read. They do this by looking at the subject line and the contents of the email, but they also factor in a reputation score for the server sending the message. Because of this, your deliverability is directly tied to the behavior of everyone else sending messages from the same server as you. Email marketing platforms do their best to protect their own reputations, and they have a few methods for doing this like shutting down accounts with too many complaints (quick reminder here to backup your list in case this happens to you) and attempting to enforce quality control measures like double opt-ins.

Double Opt-in vs Single Opt-in

Email marketing platforms harp on this one a lot, but the reality is there is no difference between an email address collected with a secondary opt-in step compared to one that wasn’t. The belief here is that someone who takes the extra step to confirm that they want to receive messages from you will be more likely to open future messages, and thus if you’re using a double opt-in process your list will have a better overall impact to the server’s reputation score than if you collected addresses using a single opt-in process. Some email platforms like Infusionsoft will actually send messages to double opt-in and single opt-in contacts from different servers, so this is something to watch out for.

But… double opt-in isn’t necessarily the only way to ensure engaged contacts and high open rates.

In fact, sometimes using your email provider’s clunky double opt-in process will be worse for the overall customer experience, and thus worse for curating an engaged email list.

Take the case of a lead magnet delivery campaign. If you’re asking someone to opt-in to receive a download, then you send them an email asking them to confirm that they want to receive that link to download, and then finally sending them the actual lead magnet delivery email after that, you’re inserting an unnecessary email into the process and thus an additional barrier to that person getting what they’re looking for.

It’s better to focus on your overall list engagement than to force a double opt-in process on all new contacts.

And yes, sometimes that means pruning cold subscribers.

Combining marketing messages with transactional messages

Email marketing platforms that send through the same servers as transactional messages will have higher overall reputation scores because millions of transactional emails are being sent and are being opened alongside marketing emails.

Transactional messages like e-commerce receipts and “reset password” emails have ridiculously high open rates. Mailchimp, for example, offers the Mandrill service, and if you use both your aggregate engagement metrics will look more favorable and thus will boost your sender reputation. ConvertKit uses a service called Mailgun behind the scenes, which you can also use for transaction messages. Another option is to use Amazon’s SES. While you cannot directly send marketing messages via Amazon SES you can set up Infusionsoft to send through Amazon SES via WeDeliver.

Sending from a Dedicated IP Address

Some email platforms offer the ability to buy a dedicated IP address to send your email from. This isolates you from the behavior of other email senders on the platform, separating you from the existing reputation of the platform. That may sound attractive, but just like a credit score no history can be just as big an issue as bad history. Managing IP reputation is more involved as well, the big platforms leverage complex techniques to maintain reputation scores that would no longer be available to you. So my advice is don’t do it!

In addition to your email platform’s reputation, you have your own sender reputation.

Independent of the server’s reputation, your domain carries a reputation score that goes with you no matter which service you send email from. Focus on boosting engagement, and make sure transactional messages that have higher open rates (e.g. e-commerce receipts) are sent from the same domain.

There are services like Sender Score that will report on your sender reputation if you want to learn more about how well you’ve been doing.

Testing, and more testing!

To reiterate, what you’re going for in building up your sender reputation is higher open and click rates. And how do you achieve that? By actively reviewing campaigns to see which subject lines are getting opened, what type of content your list likes, and split testing!

Some things to try:

  • Tailor subject lines to different segments of your list. Different audiences respond to different things, do you have both men and women on your list? Independently measure open rates for each segment and try out different variations to see what sticks.
  • Try sending messages at different times during the day. Timing can be everything, and it can sometimes be hard to predict when your list will be most engaged. Mix up days of the week, split test mornings vs. evenings.
  • Vary your call to action (CTA) placement. Open rates are one measure of engagement, click throughs are another. Optimizing this can not only boost message engagement but also helps with other metrics like email ROI.

In summary

To wrap up, deliverability is complex, but it is mostly about engagement. You’ll be far more successful if you implement identity verification technologies like SPF, DKIM, and DMARC but even with those in place the most important thing you can do is focus on your boosting your sender reputation by providing compelling content your readers want to open.

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About The Author

Bryce Hamrick

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Bryce Hamrick is an entrepreneur, business & marketing strategist, and product consultant with nearly two decades of experience in industry. Bryce has been a software engineer, product manager, and director of product management for startups as well as large enterprises. He has led teams to bring dozens of products to market and has executed numerous six-figure product launches. Today Bryce and his team focus on leveraging his product execution strategy to help businesses with growth and scale.