A 3-Tiered Approach to Solving Deliverability Challenges

By Kris Sakaluk, Senior Analyst, Data Axle

As a channel, email continues to evolve and become smarter. But at the same time, deliverability challenges still plague senders and prevent emails from reaching subscribers’ inboxes. While email deliverability is a complex topic, there are ways to effectively and reliably avoid barriers.

Deliverability challenges can usually be traced to three causes: bad data, bad creative or bad email program configuration. To consistently make it to users’ inboxes, you need clean, accurate data sent with relevant messaging and the right program mechanics. Let’s examine each of these areas in more detail.


Bad customer data can land you on a blocklist and lead to your emails being blocked by ISPs. To improve your customer data, verify email addresses as they enter your database. Verification tools include real-time verification, CAPTCHA (a challenge-response test designed to foil bots) and confirmed opt-in (in which subscribers receive a verification link that they must click to confirm their subscription).

In addition, you can collect zero-party data. Such data is information shared directly and proactively by your audience about their preferences and interests. You can use preference centers to gather information about how your audience wants to hear from you. It is also helpful to practice regular data hygiene to identify non-mailable accounts in your database and purge the list of duplicate emails, temporary emails and addresses that can’t be reached.


Email design and content have a big influence on open rates. Key to understanding what works is understanding what’s possible. For instance, images may be important to your strategy, but consider that 43 percent of Gmail users read their emails without images and Outlook’s desktop application has images turned off by default. Likewise, given that mobile is a key venue for email messages (accounting for 46 percent of all opens), marketers need to optimize their creative for mobile or risk losing engagement.

Design aside, marketers need to toe the line between writing engaging copy and triggering spam filters. To keep clear of the latter, avoid using exclamation points or special characters in subject lines and avoid words like “free,” “winner,” “guarantee,” or “check or money order” in your copy. Avoid including an excessive number of links in your copy and don’t use generic link shorteners. Create compelling calls to action—but avoid using too many.

Program Configuration

While the right data and creative are key to a successful email program and high deliverability rates, marketers need to consider the following tactics to avoid deliverability issues as well:

Practice stream separation: Use separate IP addresses to send different components of your email program. For instance, if you practice mail stream separation and the IP address off of which you send reactivation messages is blocked by Gmail, then the block only affects the reactivation component of your mailing program and won’t cause issues with the rest of your messages. But if you use a single IP for all communications, then a Gmail block would mean none of your campaigns make it to any Gmail users.

Review campaign volume and frequency: Suddenly changing your send frequencies or send volume can affect your sender’s reputation. For instance, if you normally send 100,000 emails per day, but one blast hits 2 million recipients, an ISP might consider this a spam risk and block you.

As noise increases across the digital and social landscape, email is becoming an increasingly vital channel for staying in touch with the audiences that matter most to your brand. Following the best practices above will give subscribers a better chance of hearing what you have to say.