The Definitive Guide To Email Deliverability: 10 Best Practices

Email deliverability is a measure of how often your emails land in your recipient’s inbox without being filtered into the spam or junk folder. Whether you're an SDR aiming to reach more prospects or an email marketer looking to increase ROI on campaigns, email deliverability is critical for your success.

In this blog, we’ll cover the factors that affect Email Deliverability and provide actionable tips to improve your Email Deliverability so your emails reach your audience as intended.

This Article Contains:

• What Is Email Deliverability?
• Why Does Email Deliverability Matter?
• Key Factors Affecting Email Deliverability Rate
• 10 Best Practices to Boost Email Deliverability And Avoid Sending Spam
• 5 Best Tools for Improving Email Deliverability Rate

Pro tip: One way to improve your email deliverability is with Allegrow's email deliverability tool. This solution helps you identify issues that affect email deliverability so you can fix them and boost your score for better email performance.

What is Email Deliverability?

Email deliverability is the ability for your email to get from your server to the recipient’s inbox. It’s an essential metric for both sales and marketing teams, as it dictates whether or not your leads will see your message, or whether it will end up straight in the spam folder. 

What Are The Criteria for Email Deliverability? 

When you send an email, several factors can determine its success. These include (but are not limited to): 

• The reputation of your sender domain 
• How often recipients interact with messages sent from that domain 
• How often emails bounce (i.e., the email service provider can not deliver your message and sends it back with a non-delivery response)
• Whether recipients have marked emails from that domain as spam before 
• Delivery settings set up by the recipient’s mail provider 

Email Delivery Vs. Email Deliverability

While email delivery and email deliverability are only six letters apart, there are some key differences between the two. Namely, “email delivery” describes when an email is delivered to the service provider’s server, while “email deliverability” describes when an email arrives in a customer’s inbox. This distinction is essential. Poor email delivery often suggests an issue on the email service provider (ESP) side or that the customer’s email inbox has been filled; you can always resend the message later. 

On the other hand, poor email deliverability means your message is either blocked or filtered. If this happens, you need to take steps to produce better-quality outreach. You're severely limiting your reach if your email isn’t landing in a customer’s inbox. Therefore, senders must ensure their deliverability rates are as high as possible. 

What is a Good Email Deliverability Rate?

Regarding email deliverability, ideally, you’d want all your emails to reach your recipients, but senders should aim for a deliverability rate of 95% or higher for emails landing in the user’s primary inbox.

That being said, an indicator of good email deliverability is a low bounce rate—which should be under 1%.

While you can manage most factors that determine your deliverability rate, there are also affecting factors like having spam traps in your email lists, which can be out of your control, unless you have the technology in place to identify and remove these bad contacts.

It’s important to note that most sending platforms will only show you how many of your emails bounce (meaning they get rejected from the inbox). However, this doesn’t account for emails landing in spam/junk folders which the recipient won’t see. 

Why Does Email Deliverability Matter?

Email remains one of the most effective ways to communicate with clients, particularly for online businesses. For a business to communicate effectively with its clients via email, messages must reach their intended destinations. 

Poor deliverability could mean that an important calendar invite to a customer who’s due for renewal doesn’t arrive, or a proposal towards the end of an enterprise Sales cycle is not received.

With high email deliverability, you can ensure your messages, including transactional emails, updates, and personalized offers, reach your customers, fostering ongoing engagement.   

Improved Brand Reputation: A Focus on Email Deliverability 

If an email is delivered to the recipient’s inbox, chances are they will open it and learn more about your business. This can ultimately contribute to building a solid brand reputation. 

However, if your messages are constantly rejected by their mail servers, this can eventually tarnish your brand’s image and severely impact customer confidence.  

Increased ROI: A Return On Investment For Email Deliverability 

According to reports, email marketing remains one of the most efficient ways of communication. It delivers the highest ROI, and you get $42 back for every dollar you spend. 

The projected growth is only possible when the right strategies are at play, and your emails get delivered to clients’ inboxes. Ensuring high deliverability means your messages are more likely to be read and acted upon, maximizing the potential returns from your campaigns.  

Monitor Campaign Performance: Email Deliverability Metrics 

Keeping track of your deliverability metrics helps ensure that your message reaches and drives engagement and assesses the effectiveness of your email campaigns. By monitoring email deliverability, you can better understand your emails' performance and make data-driven decisions to improve your email marketing campaign.  

Optimize B2B Email Deliverability with Allegrow’s Advanced Tools

Our email deliverability tool has unique testing capabilities for B2B inboxes. Allegrow integrates with sales engagement tools to help:

• Save you and your team from targeting harmful contacts
• Build up positive engagement for individual mailboxes
• Automatically prevent email bounces
• Get daily domain health updates 

As well as test A/B content variations, measure spam rates for each sender, and more to help you improve and maintain inbox placement.

Allegrow’s core features focus on mitigating risks associated with email sending–proactively removing harmful contacts from cadences and campaigns.

Related Reading

• Email Deliverability Best Practices

Key Factors Affecting Email Deliverability Rate

1. Reputation: How Trustworthy Is Your Email?

Sender reputation directly impacts deliverability. Email providers assess sender reputation, which includes past email engagement, the reputation of the IP address that sent the email, and the domain reputation of any links included in the email. 

Reputation can also be impacted by spam complaint rates and bounce rates, which we’ll touch on below.

2. Engagement: What Do Your Recipients Think?

Email engagement refers to how recipients interact with your emails. Most customers on third-party email lists use Gmail or Microsoft, and both ESPs now focus heavily on how recipients engage with email to determine whether or not emails make it to the inbox (or, in the case of Gmail, the folder in which they get filed). As a result, subscriber engagement with emails can cause the inbox placement rate to fluctuate as ESPs use these metrics to determine how to filter emails. 

• Spam Complaint Rate: It’s the number of emails recipients mark as spam out of all your outbound messages. The industry-acceptable spam rate is 0.1%.  Anything above that will lower your deliverability.

• Bounce Rate: It’s the percentage of your emails that bounce back or are rejected by recipients. This usually happens when you email a risky contact, which could be invalid, a spam trap, or someone with a very strong filter on incoming email. (you’ll want this rate to be below 1% for cold emails). 

• Response Rate: It’s a metric of the number of emails that receive a response out of the total emails sent. A good response rate is around 10%, but in some segments, 5% might be a reasonable target.
• Inbox Placement Rate: It’s the percentage of outbound emails that reach a prospect’s primary inbox out of your total outgoing emails. (meaning they didn’t land in spam or junk folders). You’ll want this to be above 90%. 

3. Content: Is Your Email Content Spammy?

The content quality of your emails also matters when it comes to deliverability. Specifically, email providers will evaluate everything from the language used, HTML formatting, and content relevance (per the above note on engagement) to the links included the image-to-text ratio, and the presence of an unsubscribe link.

4. Authentication: Are You Who You Say You Are?

Email authentication is setting up authentication protocols to ensure the email service provider that you’re the one sending the outreach emails and they can be trusted. 

The three major authentication protocols are:

You should also notice that email servers will check if your domain respects some security certification: 

• SPF: Sender Policy Framework (SPF) is an email authentication method that verifies a claim that a mail has come from a specific domain during mail delivery. This is done by checking if the IP address submitting the claimed mail is authorized by that domain’s administrators. It enables you to add a list of senders authorized to send email from your domain.
  
  For instance, using separate email APIs or software tools for your marketing and sales emails, you can add both services as approved senders using an SPF record. This lets your contacts know that the messages are authentic and trustworthy.
• DMARC (Domain-based Message Authentication Reporting & Conformance): DMARC adds an extra layer of security to your emails – an alignment test. It also lets you warn recipient servers about a failed email test so that they can discard or quarantine a suspicious email.
• DKIM (DomainKeys Identified Mail): DKIM uses digital signatures and encryption keys to validate your emails and prevent recipients from replying to illegitimate messages.

5. Infrastructure: Are You Equipped to Send Emails at Scale?

The more emails you send, the more important the infrastructure you use to send them becomes. For example, if you’re a high-volume sender, you need to ensure you have conducted the appropriate IP warming to be able to send emails at scale without getting flagged as spam. You also need to use feedback loops to monitor for email complaints, such as when recipients mark an email as spam, and for hard and soft bounces.

Equally, spammers usually send blasts of emails to recipients from a new domain before the recipient mailbox provider can identify and block them, which is why email warm up is a must when setting up a new subdomain or domain. 

Start by sending a small volume of messages at regular intervals to build up your reputation. Maintain the cadence during your initial cold emailing days and gradually increase the number of emails. 

Besides email volume, the frequency of sending them also affects deliverability. Email frequency is not fixed and evolves as you build your sender reputation. Start with a low frequency of emails and then increase it depending on prospect engagement

Related Reading

• How to warm up your email domain
• How to Improve Email Deliverability

Now, let’s look at some best practices that can help boost your email deliverability efforts.

10 Best Practices to Boost Email Deliverability And Avoid Sending Spam

1. Authenticate Your Email Domain

Authenticated emails let ESPs know that your messages are legitimate and originate from your end. 

‍If your contacts receive emails from a domain different from the actual sending domain, they won’t trust the emails and might mark them as spam.

‍Setting up the SPF and DKIM authentication records prevents forgery and adds encryption keys to validate your emails. 

With the DMARC protocol, you can ensure contacts that your emails are protected with SPF and DKIM, enhancing your deliverability.

2. Dedicate Subdomains for High Volume Emails 

By using a subdomain for sending a high volume of emails, you can isolate your email activities from affecting your primary domain, whilst still maintaining credibility. This separation helps protect your primary domain's reputation. 

‍How?

If a deliverability issue comes up with your email marketing campaigns, they are less likely to affect your primary domain's email deliverability. You can also customize authentication settings for your subdomains without affecting the primary domain.

‍Subdomains also help you analyze email deliverability issues easily, determine which emails are causing the deliverability issue, and sort it out before it further damages your domain reputation. 

This proactive approach ensures that your emails consistently reach the inbox and don't end up in spam folders, which can negatively impact engagement rates.  

3. Hyper-focused and healthy prospect lists

How you collect email addresses plays a large role in your deliverability rates. An optimized list-building and cleaning process ensures your email list is full of engaged users. 

When creating a list, a good strategy is to segment your contact list based on specific data points like:

• The content your prospects engaged with on Twitter or LinkedIn 
• Any change in your prospect’s current tech stack
• The reviews left by your prospect’s company’s employees on Glassdoor, etc., and so on

Sending emails tailored to your contacts’ intent and issues keeps them engaged and more likely to engage, raising your deliverability rate.

To enhance your long-term email deliverability, developing a process where you avoid reaching out to risky contacts is essential. If you don’t have a final line of defense to avoid email sending to invalid contacts, spam traps, low engagement emails, or known spam reporters you’ll see higher bounce rates. 

While email bounce rates exceeding 2.8% are likely to result in your emails landing in spam, the industry average bounce rate actually sits at 0.41%. Therefore it’s essential to aim for the lowest bounce rate possible––we recommend a maximum of 1%, ideally lower.

A high bounce rate reflects poorly on your overall inbox placement and deliverability and is a strong indicator that your emails are hitting the spam folder. Use a solution like an email Safety Net, which integrates with your sending platform to help mitigate these risks.  

4. Avoid Spammy Language and Content

Your subject lines are crucial content determining whether a user opens your emails. Spam filters have evolved to look beyond spammy words and detect excessively salesy and generic-sounding language in your emails. 

There is no absolute rule or words that, if avoided, will guarantee you a place in the inbox, but when you’re writing your subject lines, focus on the genuine value of the message without sounding pushy. If your email subject line or content makes false promises or sets sky-high expectations, the message will likely wind up in spam. 

Emails containing too many links, images, large attachments, or video files are more likely to be marked as suspicious content by ESPs. When doing cold outreach, or building up initial contact with marketing subscribers, include a maximum of two links per email–the footer counts– and no images until engagement has been established.

5. Test Your Emails Before Sending 

Firstly, you should always test your outreach campaigns by sending them to yourself to check how they look in your prospect’s inbox. You must ensure your emails are legible on mobile devices, and testing them beforehand helps you fix any formatting issues, display errors, and more.

Additionally, you should test the messages and general layout using a content A/B testing tool ahead of sending, to see which variation of the content is less likely to trigger spam filters.

You can also preview your messages on an email deliverability tool like Allegrow and resolve any problems with their design and template.

6. Clean Up Your List Regularly 

The longer you keep inactive and unengaged users on your email list, the more you risk damage to your reputation and deliverability rates. 

To enhance your long-term email deliverability, developing a process where you avoid reaching out to risky contacts is essential. If you don’t have a final line of defense to avoid emails being sent to invalid contacts, spam traps, low engagement emails, or known spam reporters you’ll see high bounce rates regularly. 

‍A high bounce rate reflects poorly on your overall inbox placement and deliverability. Use a solution like an email Safety Net, which integrates with your sending platform to help mitigate these risks. 

Providing a clear and easy way for your users to opt out of your emails helps automate the process. However, it’s also important to clean your list regularly so that it is healthy and only includes people who engage with your emails–we recommend you do this at least every 30 days.

7. Avoid Spam Traps 

Spam traps are email addresses set in place by Internet Service Providers (ISPs) and email community organizations to catch spammers “in the act” from sending unwanted emails and senders who aren’t following email best practices. 

Examples of spam traps can include:

• Email addresses that used to be genuine, but have since become dormant (although email providers still monitor them) 
• Emails that are directed to inboxes specifically monitored by IT admins or security organizations, rather than a recipient.

Pro tip: Spam traps emails addresses can only be identified by bots or email scraping tools, not by senders, which is why its paramount to use a risk analysis tool to check your email lists for spam traps.

If a sender targets a spam trap, the activity is flagged by the service provider and can even lead to you immediately getting added to a block/deny list. 

Getting yourself off a deny list is incredibly challenging, so it’s best to never end up on one in the first place. Email marketers can avoid spam traps by keeping a clean list of engaged users and never purchasing an email list.

8. Send Emails That People Love 

When improving your email deliverability, You must please two parties: your ESPs and your recipients. But if you please the latter, the former will already be taken care of. 

ESPs protect the end-user, and if the users indicate they are happy, the ESPs will continue to place your email in the inbox. Above all, if your recipients enjoy and derive value from your email, they will interact with your messages.

Customizing your outreach emails and follow-ups based on data you have about your prospects can increase this interaction.

9. Monitor Your Email Metrics 

Monitor your email performance metrics to maintain and improve your deliverability rates. 

Here's why it matters: 

• Identify Issues Early: Regular monitoring helps you spot potential deliverability problems before they become critical. 
• Track Improvements: Analyzing your metrics over time shows the impact of your deliverability efforts. 
• Optimize Your Strategy: Use data-driven insights to refine your email marketing approach. 

Important email metrics to monitor: 

• Bounce Rate: High bounce rates can harm your sender's reputation. Monitor both hard and soft bounces. 
• Spam Complaint Rate: If this rises, it's a red flag that your content or sending practices need adjustment. 
• Response Rates And Click-Through Rates: While not direct deliverability metrics, these engagement signals influence how ESPs view your emails. 
• Inbox Placement Rate: This tells you what percentage of your emails are reaching the inbox.

10. Send Short Sequences, and Sunset

Less is often more when it comes to email outreach, particularly in B2B outbound sales. Sending messages to recipients unlikely to engage can harm deliverability and your sender reputation. 

Shorter email sequences enable teams to quickly test content and determine if there’s a good fit. If engagement is low, messages can be revised, or reps can pivot to targeting more qualified contacts.

Additionally, if you’re targeting a list of email subscribers, implementing a sunsetting policy is crucial. Regularly remove unresponsive leads after a set period or number of attempts. This prevents wasted resources and minimizes the risk of damaging your sender reputation due to persistent outreach to disengaged recipients. A well-defined sunsetting policy ensures efforts focus on high-potential leads while maintaining a healthy email strategy.

A smaller, more engaged list is far more valuable than a large list of unresponsive subscribers.

5 Best Tools for Improving Email Deliverability Rate

1. Allegrow: Your B2B Email Deliverability Partner  

Allegrow is a proven email deliverability platform trusted by hundreds of corporate users to maximize inbox placement and engagement. Our customers see dramatic improvements in key metrics, with users reporting:

• 40%+ higher response rates
• 90%+ sender reputation scores
• 85% reduction in bounce rates
• Identifying thousands of spam traps and bounce risk emails each month

Deliverability Features to Scale Your Operations:

• Real-time inbox placement monitoring across a network of authentic B2B inboxes
• Spam filter testing to identify risky contacts in your outgoing emails to avoid recipient ESP’s spam trap. This helps you avoid invalid contacts and stay away from prospects who are likely to report or ignore you.
• Use email throttling and warm-up features to safely warm up your domain and subdomains safely for long-term scalability.
• Email verification and list cleaning to remove high-risk contacts
• Integrate directly with leading Sales Engagement Platforms like Outreach, SalesLoft, and Close CRM.
• Get regular updates on your sender reputation and check how frequently your messages end up in the recipient's spam box.

Integrate Allegrow with your existing email-sending platforms, and receive expert guidance on maintaining high email deliverability through dedicated 1:1 onboarding and ongoing training sessions. Whether you're launching new domains, scaling outreach programs, or working to hit ambitious sales targets, our team of deliverability experts ensures you maintain a strong sender reputation while simultaneously increasing email volume.

Identify risky contacts in your outgoing emails to avoid recipient ESP’s spam trap. This helps you avoid invalid contacts and stay away from prospects who are likely to report or ignore you.

Trusted by companies like Apollo.io, Paddle, Workvivo, and Quantum Metric, Allegrow serves revenue leaders (VPs of Sales, RevOps, CEOs) and frontline teams (BDRs, SDRs, AEs, Email marketers) who need to confidently scale their email operations without risking deliverability.

Book a free 15-minute audit to see how we can improve your email performance today! 

2. MailTrap: Your Email Deliverability Testing Environment  

MailTrap is an advanced ecosystem designed specifically for development teams and technical users to test, send, and manage email infrastructure

Key features tailored for technical workflows include:

• An in-built sandbox for safely testing email deliverability and validating emails without spamming recipients
• A reliable email API and SMTP service optimized for effective outreach
• A user-friendly dashboard with deliverability alerts and 60 days of email logs, streamlining email management and debugging

Doesn’t include: List validation or spam trap removal (you'll need something like Allegrow for that).

MailTrap also supports team collaboration, allowing you to share test environments with colleagues for streamlined workflows and comprehensive omnichannel insights.

With pricing starting at $14.99/month for 5,000 email tests, MailTrap offers an affordable, developer-friendly solution. Plus, get started with 100 free email deliverability checks on their free plan. 

3. SendPulse: Multichannel Marketing with Email Verification Features 

SendPulse is a multichannel marketing and sales platform that provides advanced marketing automation solutions, including an email verifier. The verifier works equally well with isolated emails and bulky email lists and returns accurate verification results. 

The verification process is super simple: first, you upload your mailing list in the verifying section on the website; you have a detailed report and a refined list of verified email addresses. The service grants up to 100 verifications for free; the cheapest paid plan costs around $3 for 1,000 verifications.  

Doesn’t include: Specialized email deliverability testing or advanced spam analysis as it is primarily a marketing automation platform–rather than try to use one tool for everything, consider a platform dedicated to email deliverability.

4. Glock Apps: A Solid Online Email Spam Checker  

Glock Apps is a solid online email spam checker. Its tools are designed to help you increase your email deliverability rate. 

Glock Apps includes three key tools: 

• Gappie: Real-time reports about your email domain, security, and deliverability, such as a surge of email traffic from your domain, a drop in your DMARC compliance rate, DKIM or SPF authentication failures, or changes or the SPF or DMARC records.
• Domain Checker: Protecting your domain from illegal use, including spoofing attacks and spam. 
• Inbox Email Tester: Detailed reports on where your emails land. 

Glock Apps offers four price plans covering various email marketing needs: 

• Uptime Monitor
• DMARC Analytics
• Inbox Insight
• Bundle

The latter is the most comprehensive, starting from $59 monthly for 3,600 spam tests.  

Doesn’t include: Email verification functionality. (Allegrow should be used here). Users also report that the platform user experience can be quite difficult to manage.

5. Kickbox: Email Validation and Deliverability  

Kickbox empowers businesses with technologies for best email practices, offering an autonomous approach to onboarding. Their tools include:

• Email validation
• Real-time verification API
• Blocklist monitoring
• Inbox placement analysis
• DMARC monitoring

These features cater to businesses of all sizes, enabling users to independently:

• Identify fake and invalid email addresses, including fixing typos
• Eliminate or significantly reduce bounces
• Optimize the efficiency of email campaigns

Doesn’t include: Spam filter testing, which is essential for knowing whether your emails would land in the spam folder or not, regardless of email address validation.

Boost Your Email Deliverability with Allegrow

Email deliverability is essential for the success of your email campaign. However, trying to improve your deliverability manually without any external help can be cumbersome and inefficient.

Whether you're launching a new product or trying to hit ambitious sales goals, Allegrow helps optimize your email deliverability for maximum impact. 

Book a free 15-minute audit call to learn more about our email deliverability tool today!

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