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Email remains a cornerstone of professional outreach and engagement. Yet, amidst the sea of messages flooding inboxes, one critical aspect often determines the fate of your emails – deliverability.

Did you know that over 20% of legitimate marketing emails never reach the inbox? Despite your best efforts, many of your meticulously crafted messages might end up in the spam folder, where they are unlikely to see the light of day.

Email deliverability isn't just a buzzword; it's the lifeline of your email outreach efforts. It's the difference between your carefully crafted messages reaching their intended recipients and vanishing into the digital ether, never to be seen or read.

In this comprehensive guide, we're diving headfirst into the intricate world of email deliverability. We'll break down the fundamentals and unravel the nuances between email delivery and deliverability Moreover, we'll uncover the key factors influencing whether your email lands in the inbox or gets relegated to the dreaded spam folder.

What is Email Deliverability?

Email deliverability refers to an email sender's ability to successfully deliver emails to the recipients' inboxes without being filtered out as spam or bounced back undelivered.

In essence, it assesses the likelihood that your emails will reach the intended recipients and have a chance to be opened and read rather than being relegated to the spam folder or rejected by the recipient's email server.

Email deliverability is a crucial metric for email marketers and businesses, as it directly impacts the effectiveness of their email outreach campaigns and communication efforts. Achieving high email deliverability rates requires understanding and optimizing various factors, including sender reputation, email content, authentication protocols, and recipient engagement.

Why is Email Deliverability Important for Email Outreach?

Email deliverability in email outreach cannot be overstated, as it directly impacts the success and effectiveness of your email campaigns. Email deliverability is crucial for several reasons:

1. Reaching your target audience

High email deliverability ensures that your messages land in your recipient's inboxes. Without good deliverability, your emails may end up in spam folders or be blocked entirely, making it nearly impossible to reach your intended audience.

2. Building and maintaining reputation

Email service providers (ESPs) and internet service providers (ISPs) assess the sender's reputation when deciding whether to deliver an email or mark it as spam. Poor deliverability can harm your sender's reputation, making getting your emails into inboxes even harder.

3. Maximizing ROI

Email outreach campaigns often require significant time and resources. Low deliverability rates mean your investment in content creation, design, and list management may be used if your emails reach the right people.

4. Legal compliance

Ensuring good email deliverability also means adhering to email marketing laws and regulations, such as the CAN-SPAM Act in the United States. Violating these laws can result in substantial fines.

5. Enhancing engagement

Emails that don't reach the inbox can't be opened, read, or acted upon. By improving deliverability, you increase the chances of recipients engaging with your content and taking desired actions, whether purchasing, signing up for a webinar, or simply staying informed.

6. Reducing costs

When your emails are not delivered, you may send them multiple times, thinking they were never received. This can lead to unnecessary email service fees and damage your sender's reputation.

7. Brand credibility

High email deliverability reinforces your brand's credibility. When recipients consistently receive your emails in their inboxes, they are more likely to trust your brand and view your communications as valuable.

Email Delivery vs. Email Deliverability: Understanding the Difference 

Certainly, here's the difference between email delivery and email deliverability presented in a table:

AspectEmail DeliveryEmail Deliverability
DefinitionFocused on whether the recipient's email server accepts an email without bouncing back.Encompasses the entire journey of an email, considering inbox placement, spam folder, or being blocked.
Main goalEnsure the email is accepted by the recipient's server and doesn't bounce back as undeliverable.Ensure the email is delivered and placed in the recipient's inbox, maximizing the chance of being opened and read.
MeasurementDelivery rates are the percentage of emails successfully delivered to the recipient's server.Deliverability rates consider the percentage of emails successfully delivered to the inbox, excluding those sent to spam folders or bounced back.
FocusInitial acceptance by the recipient's email server.Full email journey, including inbox placement and spam filtering.
OutcomeAddresses whether the email was technically delivered.Addresses where the email lands, influencing its visibility and engagement potential.



How Does Email Deliverability Work?

Email deliverability is a complex and multifaceted process determining whether your emails reach the recipient's inbox spam folder or get blocked altogether. To understand how email deliverability works, let's break it down into steps:

Step 1: Sender initiates the email

The email deliverability process begins when a sender, whether an individual or organization, creates an email message and sends it to the intended recipient's email address.

Step 2: Sender's SMTP server

The email is sent from the sender's email client or marketing platform to their SMTP (Simple Mail Transfer Protocol) server. The SMTP server is responsible for initiating the transmission of the email.

Step 3: DNS lookup

The sender's SMTP server performs a DNS (Domain Name System) lookup to identify the recipient's mail server's IP address. This lookup involves querying the recipient's domain's DNS records to retrieve the Mail Exchange (MX) records, which specify the location where incoming emails should be delivered.

Step 4: SMTP connection

Once the recipient's mail server's IP address is obtained from the MX records, the sender's SMTP server establishes a connection with the recipient's mail server.

Step 5: Sender authentication

To verify the legitimacy of the sender and prevent email spoofing, the sender's SMTP server may employ authentication protocols such as SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting, and Conformance).

Step 6: Content scanning

The recipient's mail server scans the content of the incoming email to check for any indicators of spam, malware, or suspicious activities. This includes examining subject lines, message body, attachments, and embedded links.

Step 7: Reputation evaluation

The recipient's mail server assesses the sender's reputation, which is determined by factors such as the sender's historical sending behavior, IP address, and the effectiveness of sender authentication methods. A positive sender reputation enhances the chances of email acceptance.

Step 8: Spam filtering

The email undergoes spam filtering, where the recipient's mail server utilizes advanced algorithms and filters to evaluate various elements, including content, sender characteristics, links, and recipient engagement patterns.

Step 9: Inbox placement

Based on the spam filtering process results, the recipient's mail server determines the placement of the email. Whether it should be delivered to the recipient's inbox, routed to the spam folder, or rejected outright.

Step 10: Delivery report

Suppose the email passes through all the checks and is placed in the recipient's inbox. In that case, a delivery report is generated and transmitted back to the sender's SMTP server, confirming the successful delivery.

Step 11: Recipient interaction

Subsequent actions by the recipient, such as opening the email, clicking on embedded links, marking the email as spam, or unsubscribing, can further influence the sender's reputation and email deliverability for future communications.

Step 12: Feedback loops

Some Internet Service Providers (ISPs) offer feedback loops that notify senders when recipients flag their emails as spam. This feedback loop enables senders to identify issues and promptly adjust their practices.

Step 13: Bounce handling 

Effective bounce handling is crucial to email deliverability. Senders must appropriately manage bounce-backs caused by invalid recipient addresses or other issues to maintain a positive sender reputation.

Step 14: Continuous monitoring and adjustment

Email deliverability is a dynamic process that requires ongoing vigilance. Senders must continually monitor their sender reputation, engagement metrics, and email campaign performance, making necessary adjustments and improvements to sustain good deliverability rates.

16 Key Factors Affecting Email Deliverability

Understanding these key factors is essential for optimizing your email deliverability. Here are the primary elements that impact it:

1. Sender reputation

Imagine your sender's reputation as a passport. It's your entry ticket to the inbox. Your reputation depends on factors like:

  • Consistency: ISPs (Internet Service Providers) love reliability. A consistent sending schedule and volume build trust.
  • Engagement: Engaging emails leads to opens, clicks, and replies, which enhance your reputation.
  • List Hygiene: A clean list, free of bouncing or inactive addresses, ensures a sparkling reputation.

For example, if you consistently send engaging and relevant content, ISPs will view you favorably, like a trusted friend. Conversely, if you engage in spammy practices, your reputation will plummet, and your emails may be in the spam folder.

2. Authentication protocols

Consider authentication protocols like a security seal on your email envelope. SPF, DKIM, and DMARC act as verification mechanisms to confirm your email's authenticity. 

  • SPF (Sender Policy Framework): SPF records verify your email's origin, proving you're not a fraud.
  • DKIM (DomainKeys Identified Mail): DKIM digitally signs your emails, ensuring authenticity.
  • DMARC (Domain-based Message Authentication, Reporting, and Conformance): DMARC tells ISPs how to handle emails that don't pass SPF or DKIM checks.

Imagine if your email were a physical letter. Without these protocols, it's like sending a letter without sealing it in an envelope – anyone could tamper with it during transit. With authentication, you seal your email with a tamper-evident seal, ensuring its integrity.

3. List hygiene

Regularly cleaning your email list is akin to decluttering your workspace. Removing inactive or unengaged subscribers ensures that you send emails to people who want to receive them, like tidying up your space for better productivity.

4. Content quality

Your email content should be like a well-prepared dish at a gourmet restaurant. It needs to be enticing, well-balanced, and free of harmful elements. Just as a poorly prepared dish can lead to negative reviews and deter future diners, subpar email content can make recipients mark your emails as spam. 

5. Subject lines and preheaders

Think of subject lines and preheaders as news article headlines and teaser blurbs. They need to represent the content and entice readers to click accurately. If your subject line promises one thing, but your email delivers something else, recipients will be disappointed and less likely to engage with future emails.

6. Sending frequency

Sending too many emails frequently is akin to constantly calling or texting someone – it can be annoying and lead to unsubscribes or spam complaints. Consider your recipient's preferences and adjust your sending frequency accordingly, just as you would respect someone's personal space.

7. Recipient engagement

Engagement metrics are like applause during a performance. High open and click-through rates indicate your audience appreciates your content, while low engagement may signify disinterest. ISPs pay attention to these metrics when deciding where to place your emails.

8. List segmentation

Think of list segmentation as a bookstore categorizing books by genre. By sending tailored content to specific segments of your audience, you ensure readers get books (emails) matching their interests. Just as a mystery novel lover may not appreciate a romance novel, irrelevant emails can lead to disengagement.

9. Spam complaints

High spam complaint rates are like customers returning spoiled food to a restaurant. It indicates dissatisfaction and can lead to negative consequences. Implementing clear opt-in processes and respecting unsubscribe requests are essential to minimize complaints.

10. Bounce management

Effective bounce management is like handling returned mail. You would only try to send letters to an address that exists. Similarly, removing hard bounces from your list is essential for maintaining list quality.

11. ISP-specific rules

Think of ISP-specific rules as different traffic regulations in various cities. You must follow the specific rules of each ISP to avoid penalties or roadblocks to your email delivery.

12. Mobile optimization

Ensure your emails are mobile-responsive, like having a restaurant menu that's easy to read on a smartphone. Many recipients check emails on mobile devices, and if your emails need to be optimized, they may appear messy and lead to lower engagement.

13. Feedback loops

Feedback loops from ISPs are like customer reviews. They provide valuable insights into how recipients perceive your emails. Just as a restaurant values customer feedback to improve its dishes, you should use feedback loops to refine your email practices.

14. Consistency

Consistency in sender information is like having a reliable brand image. When recipients recognize your sender name and email address, they're more likely to trust and engage with your emails.

15. Compliance with regulations

Adhering to email marketing laws and regulations, such as CAN-SPAM or GDPR, is like following health and safety regulations in a restaurant. Compliance avoids legal troubles and ensures ethical and trustworthy email practices.

16. Infrastructure and server configuration

Properly configuring your email infrastructure is like having a well-maintained kitchen in a restaurant. It ensures the technical aspects of your emails meet industry standards and best practices, reducing the risk of issues that can impact deliverability.

How to Measure Email Deliverability?

Measuring email deliverability involves a combination of quantitative metrics and qualitative assessments. Regularly monitoring these metrics and taking corrective actions is essential to maintaining strong email deliverability and ensuring your messages reach the right audience. Here are the tips for measuring email deliverability effectively:

1. Monitor open rates

Open rate is the percentage of recipients who open your email. Email marketing platforms provide open rate data for each campaign.

Why it is important: A healthy open rate indicates that your emails are making it to the inbox and enticing recipients to engage with your content. For example, If you send an email to 1,000 recipients, and 300 of them open it, your open rate is 30%.

2. Track click-through rates(CTR)

CTR measures the percentage of recipients clicking links or call-to-action buttons within your email. 

Why it is important: A higher CTR suggests that recipients receive your emails and find your content engaging and relevant. For say, if out of the 300 recipients who opened your email, 60 clicked on a link, your CTR is 20%.

3. Review bounce rates

Bounce rate is the percentage of emails not delivered due to issues like invalid email addresses or full mailboxes. Email platforms categorize bounces as “hard” or “soft” and provide bounce rate data.

Why it is important: A high bounce rate can negatively impact deliverability, so it's crucial to address bounce issues promptly. For example, if 20 out of 1,000 emails bounced, your bounce rate is 2%.

4. Analyze spam complaint rates

Spam complaint rate is the percentage of recipients who marked your email as spam.

Why it is important: High spam complaint rates can harm your sender's reputation and lead to deliverability issues. If 10 recipients out of 1,000 marked your email as spam, your spam complaint rate is 1%.

5. Check unsubscribe rates

The unsubscribe rate measures the percentage of recipients who opted out of receiving future emails.

Why it is important: While it's natural to have some unsubscribes, excessive rates may indicate content or frequency issues. If 5 recipients out of 1,000 unsubscribed, your unsubscribe rate is 0.5%.

6. Examine inbox placement rates

Inbox placement rate is the percentage of emails that land in recipients' inboxes, as opposed to spam folders or being rejected. Email service providers often offer inbox placement monitoring services, or third-party tools can provide insights into inbox placement.

Why it is important: A high inbox placement rate indicates good deliverability. If 800 out of 1,000 emails reach the inbox, your inbox placement rate is 80%.

7. Utilize email authentication reports

Email authentication reports, such as DMARC reports, provide insights into email authentication and potential spoofing attempts. Set up DMARC and review its reports to identify authentication issues.

Why it is important: Proper email authentication enhances your email's credibility and can prevent phishing attempts that harm deliverability.

8. Leverage email testing tools

Email testing tools, like seed lists and email previews, help you assess how your emails appear in different email clients and environments. These tools provide visual previews and testing reports.

Why it is important: Ensuring your emails render correctly and look professional improves engagement and deliverability.

9. Evaluate deliverability data from ISPs

Major ISPs, like Gmail and Outlook, offer deliverability dashboards or postmaster tools that provide insights into your email performance with their recipients. Access and review data from these tools to understand how specific ISPs treat your emails.

Why it is important: ISPs' feedback is valuable for pinpointing deliverability issues with specific recipients and domains.

10. Track sender score

Sender Score is a numeric score (0-100) that assesses your sender's reputation.

Why it is important: A high Sender Score indicates a strong sender reputation, while a low score may suggest deliverability challenges.

10 Tips to Improve Email Deliverability

Improving email deliverability ensures your messages reach recipients' inboxes and aren't flagged as spam. Here are ten actionable tips to enhance your email deliverability:

1. Maintain a clean email list

A clean email list reduces bounce rates and prevents sending to uninterested or invalid recipients. This, in turn, enhances your sender's reputation.

If you have an email list with outdated or invalid addresses, and you continue to send emails to them, it can result in high bounce rates and damage your sender's reputation. Removing these addresses ensures you're only sending to engaged subscribers.

2. Use proper authentication

Authentication protocols like SPF, DKIM, and DMARC are your email's security measures, akin to having locks on your doors. They protect your emails from being forged or altered during transmission.

Without authentication, spammers can easily send emails claiming to be from your domain, harming your reputation. Implementing authentication protocols ensures that ISPs can trust your emails.

3. Segment your email list

Segmentation is like tailoring your message to different audiences. It boosts engagement because recipients receive content that's relevant to their interests.

If you're an eCommerce company, segmenting your list by past purchase history can allow you to send personalized product recommendations to different segments.

4. Personalize your emails

Personalization adds a human touch to your emails, making recipients feel valued and increasing the chances of engagement.

Addressing recipients by name and offering customized product recommendations based on browsing history or previous purchases can significantly boost click-through rates.

5. Optimize email content

Optimizing your content isn't just about design; it's about ensuring your emails are well-received by humans and spam filters.

A well-optimized email includes a concise subject line, engaging content, and mobile-responsive design. Avoiding spammy phrases like "Get Rich Quick" or "Free Offer" is essential to pass spam filters.

6. Manage sending frequency

Sending too many emails too often can lead to fatigue and disengagement among your subscribers.

If you bombard your subscribers with daily promotional emails, they may ignore your messages or even mark them as spam. Finding the right balance in sending frequency ensures better engagement.

7. Monitor engagement metrics

Engagement metrics are like a window into your subscribers' interests and behaviors. Monitoring them helps you adapt your content and sending practices accordingly.

If you notice a decline in open or click-through rates, it may indicate that your content needs to be more relevant to your audience. You can use this information to adjust your content strategy.

8. Handle bounces promptly

Bounces are not just inconvenient; they can damage your sender's reputation. Promptly addressing bounces is essential for maintaining a good sender score.

If you ignore hard bounces (invalid email addresses) and continue sending emails to them, ISPs may view this as spammy behavior. Removing hard bounces prevents further damage to your reputation.

9. Include a clear unsubscribe option

An easy-to-find unsubscribe option is not just a legal requirement; it's a way to show respect for your recipients' preferences.

If recipients struggle to find the unsubscribe link and resort to marking your emails as spam to stop receiving them, it can negatively impact your sender's reputation. A clear unsubscribe link helps you maintain a clean list and prevents spam complaints.

10. Monitor your sender's reputation

Your sender's reputation is the cornerstone of email deliverability. Monitoring it ensures you're aware of any reputation issues before they escalate.

If you suddenly notice a drop in your deliverability rates or an increase in spam complaints, checking your sender's reputation can help you identify the cause, such as a compromised email account, and take corrective actions promptly.

Monitor and Improve Email Deliverability with Outplay

As we've explored in the ultimate guide, email deliverability is a multifaceted journey. It demands a deep understanding of sender reputation, authentication protocols, list management, content optimization, and recipient engagement.

At this juncture, we'd like to introduce you to a powerful ally in your quest for email marketing excellence: Outplay. With Outplay, you can access cutting-edge tools and resources designed to bolster your email deliverability and elevate your outreach efforts to new heights.

Outplay not only empowers you to streamline your email campaigns but also provides invaluable insights and features to help you:

  • Connect existing email accounts: Outplay seamlessly integrates with Gmail and Microsoft Office 365 for direct connections. Moreover, you can also link email accounts from various providers through IMAP.
  • Personalize and optimize content: Outplay's AI allows you to craft highly personalized emails with dynamic content and subject lines that resonate with your audience.
  • Monitor engagement: Keep a close eye on Outplay's dashboard, from open rates to spam complaints, to gauge the effectiveness of your campaigns and adapt your strategies accordingly.
  • Improve deliverability: Outplay offers deliverability analytics and reporting, helping you pinpoint and address issues that may affect your email deliverability.

So, as you embark on your journey to boost your cold email deliverability, sign up for a 14-day free trial of Outplay and experience the difference for yourself. 

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