How to Improve Email Deliverability (19 Best Tips to Follow)

Stuck wondering why your carefully crafted emails are ending up in the spam folder instead of your audience’s inbox? Poor email deliverability is likely to be your number 1 suspect, with a low deliverability rate harming your sender reputation as well as future email outreach—for you and your team.

The good news is that mastering email deliverability is easier than you think. In this article, we’ll show you how to improve email deliverability and ensure your emails reach the primary inbox, not the dreaded spam folder.

Table of contents

• What is Email Deliverability: A Quick Overview
• What are The Biggest Impacts on Email Deliverability?
• How To Improve Email Deliverability: 19 Best Tips To Follow
• Why Email Deliverability Matters To Sales and Marketing Teams

What is Email Deliverability: A Quick Overview 

Email deliverability refers to the ability of your email to land in the recipient’s inbox and not the spam folder. It’s critical for sales and marketing teams to monitor email deliverability rate, as it directly impacts whether prospects, leads, and customers alike see important messages. Whether it be a first intro to whatever you’re selling, to those all-important customer contracts. 

Deliverability is influenced by factors like your sender reputation, the quality and health of your email lists, recipient engagement with your emails, spam reports, and authentication settings configured for email service providers (ESPs). Simply put, deliverability ensures the email reaches its intended destination—the user’s inbox.

More on this below.

What are The Biggest Impacts on Email Deliverability?

Sender Reputation

Your sender reputation is like your email "credit score", and ESPs evaluate several key elements to assign this score, such as: 

Domain and Reputation 

ESPs monitor the historical behavior of the domain and IP address you use to send emails. Poor practices such as high bounce rates or frequent spam complaints can damage this reputation. Blacklist appearances can signal that your emails are untrustworthy. 

Avoiding Spam Traps

Sending emails to invalid or high-risk addresses indicates poor list hygiene and can quickly damage your sender's reputation. 

Engagement

ESPs like Gmail and Microsoft increasingly prioritize user engagement metrics when deciding whether to deliver an email: 

Positive Signals 

Actions like:

• Clicking through emails
• Email responses
• Forwarding emails
• Marking them as “not spam” sends positive signals to ESPs. 

Negative Signals 

Ignoring emails, deleting them without reading them, or marking them as spam can decrease your inbox placement rates. Engagement data helps ESPs assess the relevance of your emails to recipients, making it essential to build relationships with your audience through valuable and personalized content. 

Supporting Factors That Influence Deliverability

While reputation and engagement carry the most weight, the following also play significant roles: 

Content Quality 

Spammy language, poor formatting, and overuse of links can trigger spam filters. Plus, relevancy matters: Short, simple, emails tailored to recipient interests see better engagement. 

Authentication 

Protocols like:

• SPF
• DKIM
• DMARC 

Ensure your emails are authenticated and come from a trusted source, reducing the likelihood of being flagged as spam. 

Infrastructure

Proper domain warming, feedback loops, and bounce management are critical for high-volume senders to maintain deliverability at scale. 

Why Sender Reputation and Engagement Stand Out 

While content, authentication, and infrastructure are vital, they primarily support the outcomes driven by reputation and engagement. If ESPs detect poor engagement or consider your domain has a bad reputation, even the perfect email won’t reach the inbox. You can significantly boost your email deliverability by maintaining a clean email list, having an authenticated, warmed-up domain, and providing engaging, relevant content.

For more on why deliverability matters, what factors have the biggest impact, and how to choose the best tool for your business needs, we recommend: 

• The Definitive Guide To Email Deliverability
• The Top 10 Email Deliverability Tools: Features, Prices

How To Improve Email Deliverability: 19 Best Tips To Follow

There are many factors that can impact deliverability, but here we’ve highlighted some of the most vital (and easy to implement) best practices.

1. Authenticate Your Email Domain

Email authentication is a key step in enhancing your reputation with ESPs, as it verifies your domain identity. According to the latest guidelines, without proper authentication, your deliverability will be compromised–regardless of business size and sending volume.

Ensure you configure these three critical protocols:

• Sender Policy Framework (SPF)
• DomainKeys Identified Mail (DKIM)
• Domain-based Message Authentication, Reporting & Conformance (DMARC)

This can look slightly different for different service providers, so it’s important to follow the different guidelines on how to set this up correctly, whether you’re looking to set up records for Office365 or authenticate your domain for Google Workspace.

2. Quality Email Lists

The quality of your contact list is one of the key influencers on whether or not you see deliverability and engagement success in your email outreach. Here’s how to keep it in check:

1. Start by sourcing your data from reputable providers to ensure your contacts are valid and aligned with your target audience 
2. Regularly review and clean your lists to remove invalid email addresses
3. Risk-assess your lists to remove frequent spam reporters and users with consistently low engagement scores

It’s important to remember that creating an email list for a specific cadence is not a one-and-done task. Over time, some addresses may become outdated or harmful—up to 30% of subscribers change their email addresses each year. 

Regular list hygiene has evolved into an ongoing risk management practice. To optimize results, clean your email lists at least once a month to keep them fresh, relevant, and safe to use.

3. Make It Easy to Opt Out

Including a one-step, easy-to-use unsubscribe/opt-out option in your emails keeps you compliant with Sender Guidelines, and also reduces the chance of being marked as spam. 

By allowing uninterested recipients to opt out, you can ensure you're only sending outreach to an engaged audience.

If you’re an email marketer working with a subscriber list, you must make sure you’re only targeting active subscribers. Additionally, we recommend you use a "final notice" email to reengage inactive users or remove those who don’t respond, protecting your engagement metrics and overall deliverability. This is also referred to as a Sunsetting policy.

4. Treat Inbound & Outbound the Same

Whether a contact comes from inbound sources like a website form-fill or outbound sources like a contact database, reaching out to these contacts should be treated with the same diligence. 

1. Validate the Email address: Whether you sourced the email from a third party, or a lead offered up their email, you must check whether the address is real, and that it will not be harmful to your sender reputation if you send them communications.
2. Apply cold email best practices: When contacting a new user for the first time, the email should be simple in design, short in length, and void of links, images, and attachments. Only once a user is engaged, can you can send more elaborate email content.

In short, make sure to validate and screen all lists thoroughly, regardless of their origin, and adhere to best practices when first engaging with both outbound and inbound contacts.

5. Carry Out Contact Risk Analysis

It's important to evaluate the quality of your contacts, not just validate/verify their email addresses. Even real, active email addresses can affect deliverability if the recipients are likely to mark emails as spam, frequently bounce, or ignore your content.

Risk analysis helps identify and remove these risky contacts, improving your sender reputation. Tools like Allegrow Safety Net Everywhere streamline this process, ensuring you maintain healthy deliverability.

You can carry out free risk analysis on up to 1000 contacts at Allegrow. Book a quick call with one of our deliverability experts and they’ll explain how to get started.

6. Don’t Forget About Domain Reputation 

Email providers are increasingly prioritizing domain reputation over IP reputation, as a key metric for assessing a sender's engagement and trustworthiness. 

Domain reputation is shaped by how recipients respond to your emails, not by your domain's search engine performance. Domains that consistently generate high engagement will establish a solid reputation, whereas low engagement levels can harm domain reputation, ultimately affecting email deliverability.

8. Keep Subject Lines Simple

Subject lines play a major role in determining whether your emails land in the user’s primary inbox, and whether they are engaged with. 

Spammy or overly emotive subject lines can trigger filters or discourage opens, reducing engagement and increasing the risk of emails landing in spam. Instead, use clear, straightforward subject lines that accurately reflect the content perform best. 

At Allegrow, testing has shown that shorter subject lines—around 3 to 5 words—often drive higher engagement, with simple, direct phrasing outperforming overly salesy alternatives.

9. Provide a Preference Center

Offering a preference center is a great next step. This feature allows subscribers to choose their preferred email frequency, helping to enhance their experience and maintain engagement. 

A good example of a preference center is when both the type of email the user would like to receive, as well as providing the option of how often they receive it, are included.

Engaged contacts are more likely to interact with your emails, and ESPs notice these positive behaviors, which ultimately boosts deliverability.

Pro tip: For Marketing subscription emails, including a short statement explaining why the user is receiving these emails, is seen as good practice by ESPs and can help reduce spam rate. 

10. Set Up Custom Tracking

Custom tracking domains improve deliverability by routing your links and images through your own domain, rather than a third-party service. 

To set up a custom tracking domain, simply add a CNAME record to your DNS settings, as provided by your email hosting service. This ensures better email performance and reinforces your brand’s identity.

Pro tip: Move away from tracking open rates as a measure of deliverability. In some situations, ESPs will flag emails with tracking pixels as spam.

11. Warm Up Your Domains

Before sending large volumes of emails, it’s critical to warm up your domain. Gradually increase the volume of emails you send over several weeks to establish a positive relationship with email service providers (ESPs).

Domain warm-up can be time-consuming, but automated tools can help you simulate human-like interactions with your inbox, easing the process.

12. Segment Your Email List

A clean, segmented email list helps target your audience effectively and improve deliverability. Segmentation allows you to send tailored content that resonates with each recipient's specific interests and needs.

For example, you could create segments based on the type of software prospects are using, the funding round the account is in, or even what groups and content your prospects are interacting with on LinkedIn. 

Pro tip: The further you segment your lists, the quicker you can eliminate those contacts that are less likely to engage, and focus on scaling your efforts on those who will.

13. Use subdomains

Using a subdomain for email outreach helps protect your main domain’s sender reputation and overall deliverability. 

By maintaining separate reputation scores, subdomains ensure critical communications are unaffected–you don’t want a contract to end up in the spam folder at the end of the Sales cycle. 

Additionally, subdomains enhance analytics by enabling businesses to track and compare campaign performance, aiding in the identification of deliverability issues and supporting scalable email strategies.

They also provide a buffer to isolate and resolve issues more easily if something goes wrong. However, you should decide on a number of subdomains to create and stick to this, and all subdomains must be correctly warmed. 

Pro tip: We recommend using consistent nomenclature when creating subdomains so that recipients are less likely to suspect the email is spam. For example, mail.company.com or hello.company.com

14. Personalize Your Content

Generic email content doesn’t resonate with recipients. In cold emailing, personalization is key to grabbing attention and fostering meaningful connections.

Here are some ways to hyper-personalize your emails:

• Social Media Engagement: Reference content they've interacted with on LinkedIn or Twitter, especially from thought leaders in your niche.
• Glassdoor Reviews: Highlight themes or specific feedback from their company's Glassdoor page to show you’ve done your research.
• Job Postings: Mention relevant job openings or recent hires that align with the challenges your solution addresses.
• Technology Changes: Note shifts in their tech stack or current tools they use, signaling potential needs or challenges (use resources like BuiltWith).
• Review Insights: Leverage reviews from platforms like G2 Crowd—either one submitted by their company or feedback they've received—to address key pain points or priorities.

Additionally, ending dynamic content, using features like merge tags, and Spintax, will also help you tailor emails to individual recipients, increasing the likelihood that they’ll engage with your message.

Pro tips: Creating pattern breaks on preview texts and incorporating negative keywords at the beginning of messages are great ways to grab the attention of your users. Senders should also proactively use content A/B testing. By sending test emails to secure servers before reaching actual recipients, senders can identify content that may trigger spam filters, minimizing the chances of harming their deliverability.

15. Avoid Big Attachments and Lots of Links

Avoid sending large attachments. When ESPs have to scan content for viruses or malware, the more likely they are to perceive your content as risky. 

Additionally, excessive links can be problematic as these are often associated with phishing or marketing emails—only send them when recipients are engaged with your communications.

Pro tip: Send a max of 2 links per email (this includes the footer).

16. Only Use No-Reply Emails When Necessary

No-reply emails can frustrate users if they are trying to reach you and may result in them marking you as spam. Equally, ESPs may view the lack of engagement with such emails as a sign of spam. 

If no-reply emails are necessary for specific transactions, consider warming up and using a separate subdomain. 

For example, account setup and password-related emails could come from no-reply@accounts.domain.com. Explore more guidance on subdomain usage here.

Pro tip: You should always include a ‘reply to’ email address in the email body that a user can contact to avoid frustrations.

17. Consider Frequency

Finding the right balance in your email frequency is crucial. Too many emails can overwhelm recipients, while too few may cause them to forget about you. 

When determining the frequency at which you should contact recipients, consider the following:

1. Mailbox and Domain Status. If you have an existing mailbox and domain that has been throttled and warmed up for cold outreach then the number of emails you can safely send will be higher than if you are using a new mailbox on a new domain.

Source: Allegrow

2. How often prospects should receive emails from you within a single sequence-–we recommend 3-4 emails.
3. Size of the account you are targeting. If you are targeting one prospect at an SMB company, the days between each email send should be more spaced out, than if you are targeting multiple prospects at a larger company.

Source: Allegrow: How Many Emails Can You Send Before They're Considered Spam?

For marketers, a preference center can also help remove the guesswork, allowing subscribers to control the frequency of emails they receive.

Pro tip: Be sure to keep the frequency of your email sending consistent. Spikes in frequency after periods of inactivity can cause ESPs to consider your emails as spam.

18. Monitor Your Email Metrics

Tracking email performance metrics is essential to understanding and improving deliverability. Regular monitoring helps you spot potential issues early and fine-tune your strategy to improve outcomes.

Key metrics to track and optimize:

• Bounce rates 

If your bounce rates start to creep up, your first port of call should be your contact lists. Carry out a risk analysis on your lists to ensure that they only contain qualified, active, engaged, and safe-to-target users that won’t bounce.

• Spam complaint rates

When Spam complaint rates rise, it might be a good idea to take a look at your domain authentication setup. Using a tool that checks authentication protocols (SPF, DKIM, and DMARC) hourly is a great way to always stay on top of domain issues.

• Click-through & Response rates

If your email engagement is not where you want it to be, then you should consider a couple of factors. Firstly, is your audience a good match for your value proposition? Secondly, does the content itself need to change? You should make sure content is optimized for cold outreach, as well as test different variations to see which will work best.

19. Create a Unique Brand Identity

Building a distinctive brand identity is crucial for increasing email engagement. Consistency across your campaigns and marketing channels, such as using a custom domain and closely related subdomains is key.

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Here are some subdomain examples:

For Sales Outreach= kieran@mail.allegrow.co

For a Marketing Newsletter = kieran@hello.allegrow.co

Brand indicators like BIMI, will also boost recognition and trust with recipients, allowing you to add your brand logo and other details to emails

Why Email Deliverability Matters To Sales and Marketing Teams

1. Successful Deliverability Equals Successful Sales Email ROI

Email deliverability is the foundation for any successful sales outreach strategy. How effectively Sales and Marketing teams manage contact lists and craft email content will determine whether those emails reach the intended audience.

Email continues to provide an outstanding return on investment (ROI), with reports indicating a 4400% ROI and $42 for every $1 spent. When used strategically, email is a highly profitable channel for driving sales and fostering client relationships. 

When done well, email deliverability influences the overall effectiveness of your company’s communication. It ensures not only that revenue is maximized from commercial team efforts, but that also critical emails like proposals and contracts always reach leads and customers. 

It means your executive team can send and deliver important emails from the core company domain, and that all senders can foster strong brand credibility, which ultimately empowers the company to achieve business growth.

2. Ensuring Email Deliverability: Maximizing Campaign Effectiveness

Sales and commercial teams often dedicate considerable time and effort to email outreach—testing different versions of content, adjusting send times, and choosing the right frequency for outreach.

However, all of this work is in vain if the email doesn’t reach the recipient’s inbox. By focusing on implementing strong email deliverability best practices, teams can work more efficiently in the following areas:

Identifying and targeting high-quality leads

Conducting risk analysis on leads before adding them to your cadences and campaigns helps protect your sender reputation and ensures teams only focus on leads that are a good fit. By avoiding harmful or unqualified leads, sales and marketing teams can prioritize their time and resources on prospects with the highest potential for conversion, and not follow up on those who aren’t a good fit.

Evaluating lead sources

For cold outreach, assessing the leads lists you are working with enables you to see if the sources (like contact databases) you are gathering leads from are of good quality. It also gives you scope to test and combine more emails from data sources with varying approaches to gathering contact data.

If you're leads are coming from inbound sources, you can make informed adjustments to marketing strategies or data collection methods, ensuring your campaigns attract and target only prospects that align with your goals.

Crafting and testing content

Testing email content before sending allows teams to identify and resolve issues that could trigger spam filters. By experimenting with optimized content variations, teams can determine if the messaging or audience alignment is off and make swift adjustments, leading to more targeted outreach and better engagement.

In short, an effective email strategy involves balancing high-quality content with healthy list building and maintenance to ensure maximum engagement and sales impact.

3. Win the Inbox Competition

The world of email is crowded and competitive. Every day, 360+ billion emails are sent by individuals and businesses, including millions of spam messages. With the average office worker receiving over 100 emails each day, standing out in the inbox is a challenge for sales teams trying to connect with potential customers.

With inboxes increasingly flooded with spam, commercial teams must ensure their emails are placed in the right folder—preferably the inbox. Securing this spot means outcompeting countless other messages and gaining the attention of your audience, something that requires an understanding of email deliverability best practices. 

Adapting to Advanced Email Filtering Technologies

With the rise in email traffic, inbox providers are becoming more aggressive in their filtering techniques, using sophisticated machine-learning algorithms to block malicious content—Gmail alone blocks nearly 10 million spam emails every minute.

For sales and marketing teams, this means earning a place in the inbox is becoming more challenging. To succeed, your outreach must be relevant, engaging, and delivered at the optimal time. Maintaining high-quality email content and building long-term relationships with recipients is essential for bypassing these advanced filters and ensuring your messages are seen.

How Allegrow Enhances Email Deliverability for Sales and Marketing Teams

Allegrow is a trusted email deliverability platform helping hundreds of corporate users maximize inbox placement and engagement. 

By focusing on the identification and removal of thousands of risky contacts, with email validation, spam filter testing, and sender reputation monitoring, users can expect significant improvements in key metrics. Customers report 40%+ higher response rates, 90%+ sender reputation scores, and an 85% reduction in bounce rates.

Keen to improve your email deliverability? Let one of the Allegrow experts show you how on a quick demo.

Related Reading

• Inbox Placement vs Email Deliverability
• Folderly Alternative

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