Email Deliverability: Why It Matters and What It Takes

Learn how to send emails that make it to your contact’s inboxes.

Deliverability measures how many of your contacts receive your emails, and it’s 1 of the most important factors for email marketing success.

For your strategy to work, of course, people must first receive your emails. There’s no point in crafting perfect content otherwise. Although deliverability involves more than building an audience and pressing send, it doesn’t have to be complicated.

What happens when you send an email?

To send an email, several technical steps happen behind the scenes.

  1. First, you compose an email in a service like Gmail, Yahoo, Outlook, or on a platform like Mailchimp.
  2. Next, you click send, and the message is uploaded to a simple mail transfer protocol (SMTP), which passes the email between servers.
  3. The SMTP communicates with a domain name server (DNS). A DNS operates like a sort of online address book, which tells the SMTP where the recipient’s server is located. If the DNS cannot locate the relevant server, it will send you a “mail undelivered” message.
  4. Once the DNS locates and contacts the relevant server, the SMTPs pass the message between one another. The recipient’s SMTP then decides where the email belongs—whether that’s in their inbox, spam folder, or not delivered to them at all.

But what influences whether the SMTP sorts your email into a contact’s inbox, spam, or blocks it altogether? Several variables come into play:

  • Internet service providers (ISPs). ISPs enable access to the internet, and every internet protocol (IP) address is linked to one. There are many different ISPs, and they don’t necessarily function the same way. Some lower-budget, lower-bandwidth ISPs may struggle with larger emails, for example.
  • Email service providers or platforms (ESPs). ESPs all have different capabilities. The way in which an email is sorted, displayed, and delivered varies based on the ESP handling it.
  • Format. The way that an email is displayed can vary considerably from format to format. For example, emails typically look different on a smartphone versus a desktop. Emails can also be read via a smart speaker, which alters deliverability considerably.

Of course, you can’t choose which ISP, ESP, or format your audience uses, but there are other factors that you can influence. These variables have a big impact on deliverability:

  • Engagement. If you achieve regular engagement, this demonstrates that your audience finds value in your emails, and that increases deliverability. The secret to engagement? Segment, understand, and interest your audience.
  • Sender reputation. This is a score assigned by an ESP to a sender. It’s based on data—similar to the way a webpage gets ranked by search engines. Your sender reputation is based mostly on your audience’s engagement with your emails. But it also factors in quality of the content, the frequency of your messaging, open rates, and authenticity. A poor sender reputation will result in ISPs automatically blocking an email or sending it to the spam folder.

Build a strong sender reputation from the start.

To get into inboxes, it’s essential to have a good sender reputation. This is something which needs to be built over time (and on an ongoing basis), and it should be considered when designing any email campaign.

Here are the keys to building a good server reputation:

  • Send the right amount of emails. Over time, ISPs will identify patterns in send rates and adjust their metrics accordingly. But a major change, like a sudden, substantial rise in the volume and frequency of emails sent will alert the ISP to the possibility of a spam virus from this sender, which could result in being blacklisted or blocked.
  • Send high-quality content. Content that’s unwanted or irrelevant to your audience runs the risk of being flagged as spam, which lowers your sender reputation. Avoid this by sending high-quality, relevant content which won’t be considered “spammy.” And by providing valuable content to your audience, your unsubscribe rate should stay low, which is another important factor.
  • Get opens and clicks. The more opens and clicks your emails receive, the better your sender reputation becomes. When your emails drive actions like clicking through to your website, it shows the ISP that your audience values your emails.
  • Keep the conversation going. It’s also a very positive signal to ISPs when your contacts reply to your emails. For that reason, you should monitor replies and respond, and avoid sending from an email address that cannot receive replies.
  • Build and manage your audience wisely. Keeping a clean and engaged audience is vital to maintaining a good sender reputation. Make sure your audience is free of spam traps (fake email addresses), unengaged subscribers, unknown users, or contacts who you don’t have permission to email.
  • Avoid hard bounces. Hard bounces occur when you send an email to an address that doesn’t exist. ISPs factor hard bounces into sender reputation, because it can signal poor audience management. Soft bounces, on the other hand, happen when an email address has a temporary issue, like an inbox that’s full. If you’re experiencing a lot of bounces, you may need to change something about the way you grow your audience. For instance, you could install a double opt-in signup method to help validate your new contacts.
  • Make sure your email looks legitimate. All of your email content—including imagery and links—will be reviewed by ISPs to determine whether or not it’s spam, a phishing attempt, and any other malicious email. Watch out for broken links, misspellings, missing email headers, or excluding options to unsubscribe. These mistakes increase the odds that your email is perceived as spam.
  • Authenticate your emails. Email authentication is critical to deliverability. This vital step proves that your emails are genuinely from your brand. It’s important to maintain a secure email and website infrastructure to build trust with the ISPs.

Get into the inbox

Ultimately, a clean, engaged audience that leads to a strong sender reputation is the ingredient to deliverability. Keep an eye on your email reports and your audience data to ensure that you’re sending the right people the right emails. With knowledge of what deliverability entails, there’s nothing to prevent you from reaching inboxes.

Written by Jenna Tiffany for Mailchimp. Jenna is an expert in digital marketing strategies.