Mailgenius guides

Email Deliverability Best Practices: The Ultimate Guide For 2023

Email marketing is a powerful tool for businesses to reach their target audience, but its effectiveness heavily relies on successful email deliverability. Imagine spending hours crafting the perfect email campaign, only to find that it ends up in the dreaded spam folder. In this ultimate guide, we’ll unravel the complexities of email deliverability best practices, helping you improve your email campaigns, and ensure your marketing emails land straight in the recipient’s inbox.

Note: Try MailGenius now and maintain top-notch email best practices. Receive detailed reports to enhance your deliverability and ensure your messages reach their intended audience. Try 3 free tests today.

Email Deliverability Defined

Email deliverability refers to the capability of delivering emails to the intended recipients’ inboxes, avoiding the spam folder. In a world where email marketing is essential for businesses, understanding the intricacies of email deliverability can be the difference between a successful campaign and a wasted effort. The primary elements that impact email deliverability are:

  • Sender reputation

  • Email authentication

  • Content quality

  • List management

Enhancing email deliverability involves using a reliable sending domain and IP address from a trustworthy email service provider, avoiding spammy language and formatting, and securing recipients’ consent before sending emails. Keeping track and evaluating email deliverability aids in fine-tuning your email campaigns. Many email testing tools are available for assessing email deliverability and mail server performance.

Factors Affecting Email Deliverability

Grasping the factors that sway email deliverability paves the way for fine-tuning your email marketing endeavors. Sender reputation, email authentication, content quality, and list management all play a significant role in determining email deliverability rates. For instance, Gmail evaluates sender reputations according to their history of sending spam, which is divided into four categories: Bad, Low, Medium/Fair, and High. This evaluation determines the likelihood of an email reaching the recipient’s inbox.

IP addresses also greatly influence the sender’s reputation and consequently their email deliverability. Steering clear of spam trigger words in the email subject line, like “free,” “guarantee,” “no obligation,” etc., helps evade being marked as spam. Additionally, graymail, which refers to email that recipients have technically opted in to receive but may not actively engage with, can negatively affect email deliverability as recipients may become less active or inactive, impacting the success of your email campaign.

Utilizing a recognisable sender name to recipients can improve email deliverability, as they are more likely to trust a personalized sender name and email address than a generic one. Keeping an eye on your inactive and seldom active subscribers and devising re-engagement campaigns for contacts who’ve stopped interacting with your messages is also vital. You could send them an exclusive offer or coupon to rekindle their interest in your company or a survey to gain insight into what they would like to see in your emails.

Email Authentication: SPF, DKIM, and DMARC

Email authentication is verifying the sender’s identity to confirm that the email is not fraudulent. Implementing email authentication protocols like SPF, DKIM, and DMARC can help verify the sender’s identity, protect against phishing, and improve email deliverability rates.

SPF, or Sender Policy Framework, is an email authentication protocol that enables domain owners to designate the mail servers they use to send emails. DKIM, or DomainKeys Identified Mail, is another protocol that enables organizations to authenticate their email messages, allowing email providers to verify their origin. Having an SPF-protected domain reduces the risk of forgery, thereby decreasing the chances of being blacklisted by spam filters. Domains with an SPF record can help improve deliverability. This increases the chances of messages being sent to recipients’ inboxes..

DMARC is an effective system which adds to the areas served by SPF and DKIM. It helps authenticate and detect malicious emails, protecting the online identity of a domain. It combines DKIM and SPF to provide additional verification, allowing a receiving server to determine the action to take if an email fails the test, such as discarding it, sending it to quarantine, or treating it as usual. Moreover, senders may receive a report for each failed test, which provides a source of information should any spoofing occur or a valid email fail a test.

Building a Strong Sender Reputation

Sender reputation is a metric ESPs utilise to evaluate the quality of a sender’s email and ascertain the probability of an email from a particular sender being classified as spam or genuine. Building a strong sender reputation involves following best practices such as IP warming, maintaining low complaint and bounce rates, and ensuring high engagement levels to avoid being flagged as spam.

A high complaint rate is the primary factor that adversely impacts the sender’s reputation, while low engagement in email marketing is defined as subscribers who receive emails but do not open them. Parting ways with inactive contacts is necessary as they can tarnish the sender’s reputation and are not a profitable use of resources.

To minimize spam complaints, businesses should ensure that the email is desired and not considered spam.

IP Warming

IP warming is a process of gradually increasing the volume of emails sent from a specific IP address in order to build a positive reputation with internet service providers and enhance email deliverability. This slow and steady increase in sending volume helps in establishing a good relationship with internet service providers and enhances email deliverability.

Failing to start your email marketing by sending campaigns incrementally can be perceived as a potential spam attack by inbox providers, resulting in emails being marked as spam in the recipient’s inbox. Many online can facilitate IP warming via a schedule by engaging with your inbox in a humanized manner.

Crafting High-Quality Email Content

High-quality email content is characterized by:

  • Personalization

  • Incorporation of new and relevant information

  • Visual ease of reading

  • Purposefulness and tailoring to the intended recipient

Subject lines and preheader text play a significant role in capturing the audience’s attention and making the email content more appealing.

It is recommended to send email campaigns 2-3 times per week, or no more than once a day for daily senders. Sending too many campaigns to subscribers per day may result in subscribers flagging emails as spam or opting out of receiving further emails.

Subject Line Best Practices

Subject lines hold weight as they’re the first element recipients notice when they receive an email, thereby directly influencing if the email gets opened or not. Personalization, avoiding spammy subject lines, and ensuring brevity and relevance to the email content are some recommended strategies for constructing subject lines.

To avoid triggering spam filters and contributing to a poor sender reputation, it’s essential to understand how a spam filter works, including being aware of spam traps. Refrain from using words such as “free,” “guarantee,” “no obligation,” and so on in the subject line.

Balancing Promotional Content vs. Non-Promotional

Email service providers have algorithms that monitor the content of emails. If they detect that the ratio of promotional content to non-promotional is too high, they may flag it as spam, preventing your emails from reaching your audience’s main inbox. Striking a balance between promotional and non-promotional content proves helpful in fostering a favorable relationship with your audience and ensuring your emails are delivered effectively.

Promotional content offers the opportunity to demonstrate your products or services and generate sales. Examples of this include product announcements, sales, discounts, and other special offers. On the other hand, non-promotional content furnishes valuable information and establishes trust with your audience. This can encompass educational content, useful advice, industry news, and other content that is beneficial to your audience.

Achieving equilibrium between the two guarantees that your audience is not inundated with incessant promotions. Instead, it enables you to provide useful and educational content that keeps them interested. This balance not only reinforces your customer base but also encourages long-term relationships with your audience. Optimize your content to avoid spam filters.

List Management and Segmentation

List management and segmentation serve to regularly clean email lists, remove inactive contacts, and segment subscribers based on their engagement levels and preferences in order to maximize email deliverability.

List cleaning or email list hygiene is the process of removing invalid email addresses from a list, resulting in reduced hard bounces and improved email deliverability.

Subscriber segmentation involves dividing an email list into smaller groups based on criteria like engagement levels and preferences. Targeting content to specific groups can enhance email deliverability by providing more pertinent and engaging content to subscribers, thus increasing engagement and reducing the likelihood of emails being marked as spam.

Monitoring and Tracking Email Deliverability Metrics

For successful email deliverability, monitoring and tracking metrics like:

  • Delivery rate

  • Open rate

  • Bounce rate

  • Complaint rate

is imperative. Monitoring and tracking email deliverability metrics such as these helps businesses identify areas for improvement and optimize their email campaigns for better outcomes.

Key email deliverability metrics include:

  • Delivery Rate

  • Open Rate

  • Click-through Rate (CTR)

  • Bounce Rate

  • Spam Complaint Rate

  • Unsubscribe Rate

These metrics provide insight into the performance of email campaigns and aid in recognizing areas for improvement in email deliverability.

Email Deliverability Checklist

This 13-point email deliverability checklist can act as a useful aid for businesses in adhering to best practices and taking the requisite measures to enhance their email deliverability rates.

First, ensure that you have implemented email authentication protocols like SPF, DKIM, and DMARC to verify the sender’s identity and protect against phishing.

Next, follow IP warming best practices to establish a good reputation with internet service providers.

Craft engaging subject lines and strive for a balance between promotional and non-promotional content.

Lastly, practice effective list management and segmentation to optimize your marketing emails for better results.


In conclusion, email deliverability is a crucial aspect of successful email marketing, and understanding its complexities and factors affecting it can help businesses improve their email campaigns and reach their target audience more effectively. Implementing email authentication protocols like SPF, DKIM, and DMARC, building a strong sender reputation, crafting high-quality email content, and practicing effective list management and segmentation are all essential components to improving email deliverability.

By following the best practices outlined in this guide, you are well on your way to optimizing your email campaigns and ensuring your marketing emails land straight in the recipient’s inbox. So go ahead, take action, and watch your email deliverability rates soar.