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Best practices to ensure great delivery for your email: Part 1

In this blog series we’ll discuss how we came to the conclusion that manual account approval will help us maintain the best deliverability for all of our customers. In Part 1 we discuss how ISPs establish and track your email’s delivery reputation. Part 2 focuses on things you can do from your side to make sure your email gets delivered reliably. And in part 3 we discuss how all senders share the responsibility for good delivery, and how that led to our decision to move to a manual approval process.

Establishing and tracking email delivery reputation #

With email, reputation matters. A lot. If you want outstanding deliverability, you need an outstanding reputation, and unless you’re really familiar with the ins and outs of email delivery, your own mail servers probably won’t get you there. Reputation can mean the difference between landing in a recipient’s inbox, being quarantined in the spam folder, or just outright deleted by the provider without being delivered at all. 

Unfortunately, inbox providers’ approaches to reputation are complicated. They’re constantly improving their algorithms, and they necessarily keep them a secret so spammers can’t adapt to work around them. Fortunately, there’s plenty of information that’s publicly available, and a basic understanding of what’s happening can take you a long ways.

There’s one underlying truth to remember about reputation: it’s difficult to earn a good reputation but easy to destroy it.

There's one underlying truth to remember about reputation: it's difficult to earn a good reputation but easy to destroy it. Reputation revolves around trust, and building trust takes time. It can’t be faked, but in some ways, it can be shared. (More on that in a bit.) So let’s take a look at how inbox providers establish and track reputation.

So how do inbox providers establish and track reputation? As time goes on, inbox providers are becoming increasingly savvy about how they determine a sender’s reputation. These days, the most significant factor is engagement, but other factors like using email authentication standards and a variety of other signals combine to collectively influence whether your emails are delivered to the inbox.

Engagement #

While there are technical aspects of modern spam filtering and reputation tracking, few things matter as much as whether your recipients want and expect your emails. There are multiple factors and metrics that contribute to this, but few matter as much as whether recipients are explicitly reporting your emails as spam. The only way to prevent that is to send great emails that people want. 

Spam reports aren’t the only metric. They’re just the safest and most explicit metric. But providers pay attention to other engagement factors as well. Are people opening your emails? How long are they reading them? Are they clicking on links? Are they replying to the emails? Are they deleting them without opening them? All of these factor into engagement, and the inbox providers use them to classify your emails somewhere on the spectrum of wanted and unwanted.

Even using a no-reply address can indirectly hurt your engagement because recipients won’t reply. The result is that you miss an opportunity to increase your reputation through additional engagement on the part of the recipients.

You can’t fake engagement. Your recipients either open and read your emails, or they don’t. If your engagement is high, your reputation will be solid. If it’s low, your emails could very well end up in the spam folder or not delivered at all. Ultimately, engagement is entirely in the hands of your recipients. So higher quality and more useful emails are the only way to lift engagement.

Authentication and IP Addresses #

For the most part, reputation is tied to IP addresses, IP address ranges, and domains. For example, one of the initial attempts to mitigate spam was that ISPs considered whether an email originated from a commercial IP range or a residential range with the idea that they could effectively drop email from residential ranges. 

Now, with the move to IPV6, as IP addresses become even more disposable, providers are increasingly tying reputation to domains by relying on DKIM authentication. With reputation, there’s incredible value in controlling your own reputation because your reputation can move between providers, but at low sending volumes, you simply don’t send enough to establish a reputation. That’s where using an established email service provider like Postmark can help you get started quickly and ensure great delivery.

The first step with sending email is to ensure that you’re using a domain that you control. The second step is ensuring that you use DKIM and SPF to authenticate the messages you send. This enables inbox providers to begin to associate reputation with your domain. So when you switch providers, you can maintain that reputation even though your IP address may change. This will also help avoid markers in email like "via" tags, question mark avatars, and similar visual cues that make your messages look less legitimate. 

The other piece of reputation tracking revolves around IP addresses and IP ranges. You can maintain control of these by running your own mail servers, but unless you’re sending significant volume, you may not be sending enough to establish a reputation for your IP address. In these cases, you can either use a shared IP address with a provider or get a dedicated IP address from the provider.

At Postmark, we don’t believe that "improved deliverability" should be an up-charge.

With shared IP addresses, your reputation can only be as good as the other senders using the same IP address. Depending on how well your email service provider polices their IP addresses, that could mean delivery issues. 

With most providers you can send from their shared IP addresses for a very low cost, but those IP addresses will be poorly policed. You'll inevitably run into delivery issues, at which point those services will recommend you upgrade and pay extra for a dedicated IP address. Unfortunately, without significant volume, a dedicated IP address may not guarantee improved delivery. You'll also bear the responsibility for warming up your dedicated IP address, and that can be a tedious and error-prone process. Moreover, many corporate email providers also tie reputation to IP ranges. So if you’re on a range that’s suspected of sending spam, a dedicated IP address still may not help, and your delivery could still suffer.

At Postmark, we only offer to switch customers to a dedicated IP address when they reach a volume where it makes sense to do so. We stand by our shared IP addresses, and you'll receive the same high quality of delivery regardless of how much or how little you spend. For lower volume senders, you’ll see better delivery on a well-policed set of shared IP addresses than you would on a dedicated IP address.

Garrett Dimon

Garrett Dimon

Husband. Father. Tinkerer. Mountain biker. Snowboarder. Used-to-be basketball gym rat.