Email Deliverability: Why it Matters & How to Improve It

Why is email deliverability important?

There are many reasons why email deliverability is so important. As mentioned above, email campaigns delivered to a subscriber's spam folder are more likely to be overlooked or even deleted, and marketing emails are useless if you can't get the recipients to read them. As a result, the lack of email engagement may affect your campaign data and increase the likelihood of your emails getting marked as spam.

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 mail 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, email spam filter, or blocks it altogether? Several variables come into play:

• Internet service providers (ISPs). An internet service provider gives internet access to subscribers. 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). Email service providers all have different capabilities. How 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.
• Your IP address. The IP address from which you send emails also impacts deliverability. ISPs and email providers track the reputation of IP addresses to determine if they're likely sources of spam. A dedicated IP address can give you more control over your sender reputation. On the other hand, shared IPs can be affected by the sending practices of others using the same address.

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 keep your audience interested.
• Sender reputation. This is a score assigned by an ESP to a sender. It's based on data—similar to how search engines rank a webpage. Your sender reputation is based mainly on your audience's engagement with your emails. But it also factors in the 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.
• Your domain reputation: Similar to IP reputation, domain reputation measures the trustworthiness of your sending domain. Email providers assess the history of emails sent from your domain to determine if they're likely to be legitimate or spam. Factors like engagement rates, spam complaints, and adherence to email best practices all contribute to your domain reputation. A good domain reputation can improve email deliverability even if you change IP addresses.

To get into inboxes, it's essential to have a good sender reputation. This is something that 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

The best way to send emails successfully is to start by sending a limited number. Sending out bulk emails can make your IP address look like nothing more than spam to your subscribers. It's best to start with small batches and be careful not to send too many to any user in one day. Take it a step further and ensure you aren't sending out emails daily.

Over time, ISPs will identify patterns in send rates and adjust their metrics accordingly. But a significant 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 denylisted or blocked.

However, the more you grow your subscriber list, the more trustworthy your IP address will look. It pays to study others in your industry to determine the most appropriate email sending frequency. If you are above or below the industry standard, your emails may not be as effective.

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 and can land your emails in the spam folder. Avoid this by sending high-quality, relevant content which won't be considered “spammy” or trigger spam traps (fake email addresses ESPs use to identify who is sending spam.

By providing valuable content to your audience, you'll keep your messages out of the spam folder and maintain a low unsubscribe rate, which is another important factor in email deliverability. Remember, email service providers are constantly refining their algorithms to protect users from unwanted emails, so staying focused on quality content is crucial for long-term success.

Increase opens and clicks

The more opens and clicks your emails receive, the better your sender reputation becomes, which directly impacts your inbox placement. When your emails drive actions like clicking through to your website, it shows the ISP that your audience values your emails. This engagement can help you maintain good email deliverability, as internet service providers are more likely to place emails from senders with high engagement rates directly in the inbox.

Additionally, focusing on increasing opens and clicks can help you identify and manage inactive subscribers. Monitoring which subscribers consistently fail to engage with your emails allows you to implement re-engagement campaigns or consider removing these inactive subscribers from your list.

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 in a timely manner. Moreover, avoid sending emails 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 used to identify and monitor spam senders. Even just one spam trap in your list can damage your sender reputation if you unknowingly email it.

Additionally, regularly remove unengaged subscribers, unknown users, and contacts who haven't given you explicit permission to email them. Maintaining a high-quality email list will help improve deliverability rates and keep you out of the spam folders of engaged subscribers.

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 a full inbox. If you're experiencing a lot of bounces, you may need to change how you grow your audience.

For instance, you could install a double opt-in signup method to help validate your new contacts. This is when a user submits their email address and they get an email in return asking them to confirm it.

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. Maintaining a secure email and website infrastructure is critical in building trust with the ISPs.

Use a reputable email service provider

Choose an email service provider with a reputation for deliverability.

Reputable providers have established relationships with ISPs and sophisticated spam filters, which can significantly improve your chances of reaching the inbox. They often offer tools to help you deal with complex spam filter algorithms and improve your overall email performance.

Monitor and manage your sender score

Your sender score is a metric ISPs use to determine whether they should deliver your emails to the recipient's inbox or spam folder.

Regularly check your sender score using the available tools and take steps to improve it if necessary. This may include cleaning your email list, improving engagement rates, and following best practices for email content and frequency.

Segment your email lists for targeted sending

Segmentation allows you to send better, relevant content to specific groups within your audience. Tailoring your communications to the interests and behaviors of different segments can help you improve engagement rates, which in turn positively impacts your deliverability.

Segmented lists often see higher open rates and lower unsubscribe rates, both of which contribute to a better sender reputation.

Use a custom IP address

Consider using dedicated IP addresses for your email campaigns. Unlike shared IPs, dedicated IP addresses give you complete control over your sender reputation. With dedicated IP addresses, your deliverability isn't affected by the sending practices of other companies.

Using your very own IP address can be particularly beneficial for high-volume senders or businesses with strict deliverability requirements. However, remember that maintaining a good reputation on a dedicated IP requires consistent sending practices and volumes.

Reaching your subscribers' inboxes consistently isn't always easy. While there's no guaranteed formula for 100% deliverability, following email marketing best practices can improve your chances of success.

Implementing a comprehensive strategy encompasses list management, testing, performance analysis, and staying current with industry standards so that you can maximize your email deliverability rates and ensure your emails reach their intended audience.

Regularly clean your email list

Maintain a high-quality email list by regularly removing inactive subscribers, bounced email addresses, and any addresses that have marked your emails as spam.

Include a clearly and easily accessible unsubscribe link in every email that lets recipients opt-out if they no longer wish to receive your communications. This process complies with anti-spam laws and helps maintain a clean list of engaged subscribers.

Perform deliverability tests

Before sending out large campaigns, conduct deliverability tests to identify potential issues. These tests can help you spot problems with your email content, formatting, or sender authentication that might trigger spam filters.

Many email service providers use built-in testing tools you can use to simulate how your emails will perform across different email clients and devices.

A deliverability test typically involves sending a sample of your email to a variety of test email addresses across different email providers. These tests check for several factors:

• Inbox placement: Does your email land in the primary inbox, promotions tab, or spam folder?
• Rendering: How does your email look across different email clients and devices?
• Authentication: Are your SPF, DKIM, and DMARC records set up correctly?
• Content analysis: Does your email content contain any elements that might trigger spam filters?
• Link checking: Are all the links in your email working and not blacklisted?

Regularly performing these tests before sending your campaigns can help you catch and fix potential deliverability issues early, improving your overall email performance and inbox placement rates.

Analyze and act on email performance metrics

Review key performance metrics regularly, such as engagement rates, bounce rates, and spam complaints. These indicators tell you about your email campaigns' effectiveness and highlight areas for improvement.

For instance, a low open rate might indicate that the issue is with your subject lines or sender name. To improve engagement, you can experiment with different subject line styles, personalization, or sender names.

Meanwhile, if your open rates are good but CTR is low, your email content may not be resonating with your audience. Test different content formats, call-to-action placements, or offer types to boost engagement.

High bounce rates can harm your sender's reputation. Regularly clean your list to remove invalid email addresses. Implement a retry strategy for soft bounces. For hard bounces, remove these email addresses immediately, as they are spam traps.

Use A/B testing to systematically improve these metrics. Test elements like subject lines, content, send times, and segmentation strategies. Remember, small improvements can compound over time to significantly boost your overall email performance and deliverability.

Stay updated with email deliverability best practices

IPS and email clients frequently update their algorithms and policies, so staying informed is a good idea to maintain high deliverability rates. You can follow industry blogs and newsletters like your email marketing program's blog to stay informed. These often provide timely updates on industry changes and best practices.

You can also monitor ISP postmaster pages. Major ISPs like Gmail, Yahoo, and Microsoft have postmaster pages that provide guidelines and updates on their spam filtering practices.

Additionally, stay informed about legal changes. Business email communications are subject to regulations, such as CAN-SPAM, GDPR, and CCPA. Keep abreast of any changes to these laws that might affect your email practices.

Key takeaways and next steps for optimal email deliverability

Whether your emails are delivered can make or break your email marketing efforts.

Focusing on a good sender reputation, maintaining a clean and engaged audience, sending high-quality content, and monitoring your performance metrics can help significantly improve your chances of reaching subscribers' inboxes. Consistently apply these strategies to ensure your messages reach the intended recipients and drive engagement and conversion.

Use Mailchimp to streamline and optimize your email deliverability. Our suite of marketing tools can help identify and resolve deliverability issues, target the right audience, and measure your performance.