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Preventing Deliverability Issues: 3 Things to Check Before You Send Your Next Campaign


When it comes to deliverability, many marketers take a reactive approach. Too often, deliverability only becomes subject of attention when things go wrong, like a drop in deliverability rates or decreased open rates. Rather than troubleshooting causes for deliverability issues when it’s already too late, taking a proactive approach and following deliverability best practices can help you avoid many common issues in the first place.

The deliverability factors you can’t check before you send—and the ones you can

Whether or not your email makes it to the inbox depends on a set of different factors. Many inbox providers rely on user feedback to determine whether or not an email should be treated as spam. In other words, if many of your subscribers mark your email as spam, this makes it more likely that the inbox providers like Gmail, Yahoo! Mail, or place your email into the spam folder, too.

Adapting to Consumers New Definition of Spam

While subscriber behavior is hard to gauge before the send, it’s not the only factor that impacts your email’s deliverability. In fact, there are quite a few other factors that inbox providers consider when deciding whether or not your email deserves to be delivered to the inbox—and many of them, you can check and optimize before you send. Here’s how:

Is your authentication set up for success?

Just as air travelers show their passports and plane tickets, emails must pass through authentication to prove that an email is from who it says it’s from. If your infrastructure and authentication aren’t set up correctly, inbox providers might have trouble confirming that you’re a legitimate sender—which might prevent your email from making it to the inbox.

Here are the three most important authentication protocols that many inbox providers consider when deciding whether or not a message is legitimate:

  • Sender Policy Framework (SPF): SPF allows mail services to double check that incoming mail from a specific domain has, in fact, been sent from an IP that the sender has authorized. SPF protects the envelope sender address by comparing the sending mail server’s IP address to the sending IP addresses noted in their published SPF record.
  • DomainKeys Identified Mail (DKIM): DKIM is an identifier that validates that your email is associated with your domain. It allows your organization to claim responsibility for your email as part of the authentication process.
  • Domain-Based Message Authentication, Reporting, & Conformance (DMARC): DMARC is an email authentication signing policy that works along DKIM and SPF. It allows a domain owner to protect their domain from being used in phishing and spoofing attempts.

If you’re unsure about whether your emails are being properly signed using SPF, DKIM, and DMARC, run your email through Litmus Spam Testing. We’ll notify you if we spot any issues— and provide actionable advice for how to fix them. 

Is List-Unsubscribe enabled for your campaigns?

Some of the most popular inbox providers like iOS Mail, Gmail, and support list-unsubscribe. The prominent unsubscribe option makes it easy for subscribers to get off your mailing list without having to find the unsubscribe link in the footer of your email. This not only helps keep your list clean, but it also reduces the risk of spam complaints: 50% of consumers have marked email as spam because they couldn’t easily figure out how to unsubscribe, according to our joint research with Fluent. The unsubscribe banner makes unsubscribing a more obvious option, preventing people from hitting the dreaded “Mark as spam.”

Inbox providers can only provide a native unsubscribe link if they find list-unsubscribe information in the header of your email. Before your next send, check whether your email contains a list-unsubscribe header.

Does your email contain a list-unsubscribe header?

Litmus Spam Testing checks whether your email is set up to support list unsubscribe—and provides you with actionable advice in case it’s not.

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Are you blocklisted?

Blocklists are lists of IP addresses or sending domains that are seen to be sending spam. Inbox providers take blocklistings seriously when deciding whether or not an email is delivered to the inbox or not.

Being blocklisted is more common than you might think. That’s because in many cases, a handful of sends to a spam trap—or in some extreme cases a single email—can cause a blocklisting and might send your next campaign straight into the spam folder. Additionally, an email that links to a site with a poor reputation or a domain that’s listed on a domain blocklist may encounter deliverability issues, too. In our 2017 State of Email Survey, 15.1% of marketers said their companies’ marketing emails had been blocklisted during the past 12 months.

If you find yourself on a blocklist, hold off sending email until you’re able to pinpoint what caused the listing. Continuing to send without a resolution plan may only hurt your sender reputation more. That’s why ensuring your brand isn’t listed on any blocklists is a crucial step before sending your next campaign.

Automate blocklist checks

Most blocklists offer online tools that allow you to check whether your domain or IP is listed. Still, checking each of the popular blocklists manually can be a cumbersome process. Automate this process with Litmus Spam Testing. Scan your email against a set of key blocklists with a single test and get notified if your IP or domain is listed on any of them.

If you find yourself listed, take the necessary steps to get your brand off the blocklist—this typically includes finding out what got you listed in the first place, fixing the issue, and submitting an unblock request to the blocklist provider.

Make it to the inbox, not the spam folder

Identify issues that might keep you from the inbox and get actionable help for how to fix them with Litmus Spam Testing.

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Bettina Specht

Bettina Specht

Bettina Specht was the Senior Content & Lifecycle Campaigns Manager at Litmus