Email Deliverability Best Practices: Boost Inbox Rates

If you’ve ever sent an email campaign only to find that a large portion of your audience never saw it, you’ve already encountered the importance of email deliverability. Yet, in most cases, people aren’t sure what causes these issues or how to fix them.

This article provides fundamental knowledge about email deliverability and presents proven methods to enhance your email delivery success rate for better audience interaction.

What is Email Deliverability?

Email deliverability measures how many of the emails you send are accepted by internet service providers. The email deliverability rate is the number of successfully sent emails as a percentage of all the emails you send. 

Email deliverability covers your message’s entire journey, from the server to the recipient’s inbox.

Email deliverability vs. delivery

People often use “delivery” and “deliverability” like they mean the same thing — but they don’t.
Delivery just means your email made it to the recipient’s mail server. It didn’t bounce, it wasn’t blocked — it technically got through. But that doesn’t mean it reached the inbox. It could still be sitting in spam or the promotions tab, where most people never look.

On the other hand, deliverability is about where your email actually lands after it’s accepted by the server. It’s what decides whether your message shows up in the inbox or gets buried somewhere else.

A lot goes into that: your sender reputation, whether your domain is authenticated (SPF, DKIM, DMARC), how people interact with your emails, and even the words you use in your subject line.

Think of it this way: delivery gets your email to the door; deliverability gets it inside the room.

Why Email Deliverability Matters in Email Marketing

Email deliverability is of crucial importance for your ROI. A high email deliverability rate means that your messages are likely to be seen and engaged with by the intended recipients. Some important metrics affected by email deliverability include: 

• Open rates and click-through rates: When emails reach the inbox, it’s more likely that the recipient will open and engage with them.
• Conversion rates and revenues: Higher visibility often translates into opportunities for conversions.
• Campaign effectiveness: High email deliverability means your entire email strategy performs better.

Poor deliverability can severely impact open rates, engagement, and brand reputation. When emails do not reach inboxes, it can result in:

• Decreased visibility and low engagement with your content
• Reduced ROI on email marketing efforts
• Damage to sender reputation, which can impact the effectiveness of your future campaigns 
• Loss of trust from subscribers after not receiving important information on time

Key Factors Influencing Email Deliverability

There are several factors that can affect your email deliverability:

• The reputation of the sender: Your history of sending practices and recipient engagement in the past can play an important role in how ISPs treat your emails.
• Authentication protocols: The Implementation of SPF, DKIM, and DMARC can help you verify your identity and prevent email spoofing.
• Quality of your email content: Is your email relevant? Is it accurate? Does it provide value? The relevance and quality of your emails can affect your reputation, engagement, and email deliverability. 
• List hygiene: Make sure your subscriber list is always up-to-date and engaged with your emails. 

Common Email Deliverability Challenges

Below are some common email deliverability challenges that senders face in their email marketing campaigns. 

Spam filters and content-based filtering

Spam filters make use of complex algorithms to analyze email content, sender information, and recipient engagement. In order not to trigger these filters, you should:

• Never use spam trigger words in subject lines and content. Such words include “free,”  “limited offer,” “unlimited,” “no cost,” “claim,” and numerous others.
• Keep a consistent sending volume and frequency. Try to avoid sudden spikes in email volume, as this can look suspicious to internet service providers.
• Keep your email content relevant and valuable to your recipients. Engagement metrics affect the way spam filters assess your emails.
• Use a balanced mix of text and images. Note that including too many images can trigger spam filters.

Bounce rates and handling undelivered emails

Bounces occur when emails can’t be delivered. There are two types of bounces:

• Hard bounces: These are permanent delivery failures that are due to invalid addresses or non-existent domains. These should be removed from your list immediately.
• Soft bounces: These refer to temporary issues like full inboxes or server problems. Monitor soft bounces and remove addresses that consistently bounce.

You can reduce bounce rates by taking the following steps: 

• Clean your email list to remove invalid or inactive addresses.
• Make use of double opt-in to make sure only valid and relevant email addresses are added to your list.
• Monitor and remove consistently bouncing addresses to maintain list quality.

Blocklists and their impact on sender reputation

Being on a blocklist can damage your sender reputation and deliverability. Blocklists are databases of IP addresses or domains that have been flagged for sending spam or engaging in suspicious email practices. You can try to avoid blocklists if you: 

• Do not purchase email lists. Only send to recipients who have truly opted in to receive your communications. Purchased lists will most often give you nothing but irrelevant, uninterested recipients. This is where “quality over quantity” should definitely be your priority. 
• Monitor your sender reputation.
• Keep good email list hygiene by removing unsubscribes and bounced addresses as soon as you notice them. 
• Respond immediately to user unsubscribe requests.

Sender reputation and domain trustworthiness

Your sender reputation is a score assigned by ISPs based on your sending practices.  To have a good reputation, you should: 

• Send only relevant, engaging content that recipients want to receive.
• Keep a consistent, balanced sending behavior and avoid spontaneous, high-volume blasts.
• Encourage recipient engagement by creating valuable, interactive content.
• Address deliverability issues as soon as you detect them. 
• Use a dedicated IP address for sending emails if you have a high volume of emails.

Authentication issues

Email authentication helps prevent email spoofing and phishing and improves email deliverability. Try to implement these key authentication protocols:

• Sender Policy Framework: SPF is a crucial email authentication method implemented through DNS TXT records. It helps determine a list of valid, authorized IP addresses and servers permitted to send emails on your domain’s behalf. An email sent from your domain contains the IP address of the sending server and the domain’s email service provider. These details are stored in your DNS as an SPF record (you can create one with a trusted SPF generator to ensure maximum accuracy). 

Once the recipient’s mail server receives your email, it conducts a verification process. The server verifies the legitimacy of the sender by comparing the IP address of the incoming email against the Sender Policy Framework (SPF) record linked to the sending domain. Based on this verification process, the email is marked as either SPF pass or fail to avoid different forms of unauthorized use. 

• DomainKeys Identified Mail: DKIM refers to the standard email authentication protocol that uses a private key for assigning a dedicated cryptographic signature to validate emails in the server of the receiver. It helps to check the legitimacy and authenticity of all incoming emails. The server of the receiver can use the public key to decode the DKIM signature and see if the email has been manipulated in the transmission process or has stayed intact.
• Domain-based Message Authentication, Reporting, and Conformance: DMARC specifies how receiving servers should handle authentication failures and allows domain owners to receive reports on authentication results.

Best Practices to Improve Email Deliverability

Here are the best practices to help you boost your email deliverability: 

Authenticate your emails with SPF, DKIM, and DMARC

Email authentication protocols like DMARC, SPF, and DKIM work together to verify your identity as a sender and protect against email spoofing. When you carefully and correctly implement these protocols, you will see an improvement in not only your email deliverability but also in your overall safety and protection from phishing attacks.

Keep your email list clean and engaged

As discussed already, you should try to remove inactive subscribers who haven’t engaged with your emails in 6-12 months. You should take this action from time to time to ensure the list is always updated. 

Never use purchased email lists as they can contain invalid or unengaged addresses and not bring any value to your email marketing efforts (they might in fact harm your efforts). Instead, build your own lists with effective marketing strategies (e.g., giving a free e-book to those who subscribe, giving a complimentary demo session, etc.). Use double opt-in for new subscribers so that there are no irrelevant or uninterested joiners. 

Once you have the list, try to segment it based on engagement and preferences to send more targeted, relevant content.

Create high-quality, relevant content

Provide valuable, informative, verified content in your emails, and try to make the information as personalized as possible. This is why understanding your target audience, their preferences, behavior, and demographics is crucial for better content and higher engagement. 

Avoid sales-heavy content or a highly promotional tone, as these can push people away and make you come across as too desperate to sell your products and services. 

Optimize sending frequency and timing

Do not overwhelm your subscribers with too many emails. You can test different sending times to maximize engagement based on your audience’s habits.

When your sending patterns are consistent, this can help you establish predictability with recipients and ISPs and result in higher engagement. 

Ensure mobile-friendly email design

Use responsive design templates that you can adapt to different screen sizes and devices.

Also, keep subject lines concise (30-40 characters) for optimal mobile viewing. For mobile reading, try to use a single-column layout since it makes the reading experience easier and more enjoyable on mobile devices. 

Avoid spam trigger words and formatting mistakes

Do not use all-caps text and spam trigger words in both subject lines and email body, and refrain from excessive punctuation. Aim for a balanced text-to-image ratio with at least 60% text. Another good practice is to use alt-text for images to provide context in case some or all of the images are blocked. 

Monitor and improve sender reputation

Use digital and email deliverability tools to track your reputation. If you detect any issues, try to address them at your earliest convenience so that you can maintain a good sender score.

Use a reliable Email Service Provider (ESP)

Choose an ESP with strong deliverability features and support. Leverage your ESP’s analytics and reporting tools along with built-in features for list management, segmentation, and automation.

Final Thoughts

Remember, good email deliverability is not about one single email getting delivered to your intended recipient’s inbox or you having a good short-term ROI from your marketing campaign. It’s about the long-term relationship between you and your subscribers, your domain and business reputation, and the long-term ROI of your email marketing campaigns. 

Understanding how important email deliverability is for your long-term business success should motivate you to consistently monitor and test your email content, email sending practices, and overall email health. Additionally, you should try to be as flexible as possible and always adapt to changing trends, standards, and regulations for a relevant and attractive online presence.

Frequently Asked Questions

What affects email deliverability most?

A few key things decide whether your emails land in the inbox or get flagged as junk. Your sender reputation is a big one; if you’ve had lots of bounces, spam complaints, or inconsistent sending, inbox providers start to lose trust. Your list quality matters too. Sending to outdated or purchased lists can hurt your credibility fast. Then there’s your content and engagement. If people aren’t opening, clicking, or interacting, that signals to platforms that your emails might not be valuable.

How often should I clean my email list?

Your email list requires periodic cleaning every three to six months for optimal results. Your email campaigns will achieve better deliverability and maintain email law compliance when you eliminate addresses that are inactive or produce bounces or those that are invalid.

What’s a good sender reputation score?

The sender reputation score ranges from 0 to 100 points. A sender reputation score above 80 indicates excellent deliverability with minimal spam risk. Deliverability problems occur when your sender reputation score falls below 70, as this indicates high bounce rates and spam complaints.

• About
• Latest Posts

Milena Baghdasaryan

Content Specialist at PowerDMARC

Milena is a skilled writer and content creator with 7+ years of experience in crafting engaging content on IT, cybersecurity, virtual events, and more. She has a proven track record of delivering high-quality work for international magazines and is a graduate of prestigious institutions such as New York University Abu Dhabi, UWC China, and the College of Europe.

Latest posts by Milena Baghdasaryan (see all)

• Best Email Deliverability Tools: Improve Inbox Placement - November 18, 2025
• Email Deliverability Best Practices: Boost Inbox Rates - November 11, 2025
• Top Email Deliverability Solutions for Better Inbox Placement in 2025 - October 24, 2025