Cold Email Deliverability 101 — The Ultimate Guide for Salesreps

The main medium of sales outreach is via email. It’s used for cold outreach, nurture sequences, and more. Studies have also shown that eight out of ten prospects prefer talking to reps over email, which further cements the platform as the king of outreach.

Email remains one of the strongest and most effective mediums of communication for any sales rep.

But what happens when your emails don’t reach your prospects?

You don’t book any meetings, and you don’t close any deals.

You throw away one of the most powerful tools in your arsenal, and more often than not, you do this unknowingly.

That’s because email deliverability is one of the most critical — and, unfortunately, one of the most overlooked — parts of your outreach.

Email deliverability determines if your emails even reach your prospect’s main inboxes, and therefore, determines if you book that meeting.

However, deliverability is a complex web of various technical aspects that constantly change.

For the busy sales rep, learning about deliverability, keeping up with these ever-changing rules, and enacting the according changes takes valuable time out of your day. Time that could have been spent on sales-related tasks, and closing important deals.

Therefore, we’ve created the ultimate deliverability guide for sales reps looking to land in prospects’ primary inbox and therefore, increase the number of meetings booked.

A Pro Guide on How to Write a Cold Email in 2023

What Is Deliverability?

Simply put, deliverability is the capability of an email to reach the recipient’s primary inbox.

This is calculated through deliverability rate, which is the percentage of emails accepted by the Internet Service Provider.

But, there is a difference between deliverability rate and delivery rate. They may sound similar, but what they represent is critical for any SDR and your outreach.

Let’s explain the difference with an example.

An image illustrating the difference between deliverability rate and delivery rate.

Delivery Rate

Delivery rate is the percentage of emails that reaches your prospect’s inbox.

Let’s explain it with an example:

An SDR sends ten emails to his prospects.

Nine out of the ten emails reach the recipient’s inbox.

Therefore, your delivery rate is 90%.

Deliverability Rate

A prospect’s inbox consists of the various folders and tabs, such as the primary inbox, promotions tab, the social tab, and the spam folder.

Deliverability rate measures the percentage of emails that reaches your prospect’s primary inbox.

Let’s explain it with an example:

An SDR sends ten emails to his prospects.

Nine of those emails reach his prospects’ inboxes.


Four of them land in the primary inbox.

Three of them land in the promotions tab.

Two of them land in the spam folder.

Therefore, the deliverability rate is 40%.

The difference between these two numbers is huge, and can make-or-break your outreach. Delivery rate only lets you know whether your emails have landed at all.

Deliverability rate gives you a much more nuanced idea of where your emails land — that is, if you hit their primary inbox or not.

What Determines Your Deliverability?

There are various factors that determine your deliverability. They work in tandem to ensure your emails reach your prospects’ primary inbox, and so it’s critical that you maintain these factors properly.

1. Email Authentication

Email Authentication is the process by which the system determines if a sender is legitimate.

This process occurs even before your email reaches your prospect’s inbox. Your email is tested to ensure that it comes from a safe origin. This is a technical solution that most end-users don’t have direct access to. It’s mostly used to counter spam, which can deceive the recipient.

However, you, the salesperson, aren’t spam. So, it’s crucial that you authenticate your emails to boost customer confidence and land in your prospects’ inbox and not their spam folder, or even worse, be rejected completely.

There are several email authentication protocols, all which operate differently. Before we break down the various components, it’s important to know that setting up multiple protocols to increase your chances of reaching inboxes and act as a fail-safe for your outreach.

The three primary protocols are:

  • Sender Policy Framework (SPF)
  • Domain Keys Identified Message (DKIM)
  • Domain-based Message Authentication, Reporting and Conformance (DMARC)

There are more protocols, but these are the three most important and will affect your deliverability the most.

Sender Policy Framework (SPF)

Sender Policy Framework (SPF) is a record that is saved to the domain’s DNS.

It is essentially a list of authorized IP addresses that are allowed to send emails from a given domain. The actual process is very simple:

  • When an email arrives at your prospect’s inbox, a DNS check is performed.
  • If the IP address matches the list of authorized addresses, then the SPF test is positive. The email is allowed to reach the inbox.
  • If the IP address does not match, then the SPF test fails. This is called a Soft Fail. The email is still accepted to the inbox, but since it failed the SPF test, it is discarded.

Sender Policy Framework is a widely adopted method for email authentication. Due to this, it is a must-have for valid email delivery.

Domain Keys Identified Message (DKIM)

Domain Keys Identified Message (DKIM) is a digital signature that is encoded into the email when it is sent. This will be validated once it reaches the email recipient.

Here’s how the process works:

An image illustrating displaying the DKIM process.

  • A public key is created and added to the domain’s DNS. This is an additional part of DKIM record but is only possible if you configure DKIM.
  • Once the email is sent, a digital signature is created with hashed details on the email header and footer, and the encrypted individual private key.
  • Once the email arrives, the server searches for and retrieves the public key. This is used to recreate the hashes and compare it to the ones it has received.
  • If the match is correct, then the test is successful and your email reaches the prospect’s inbox.
  • If this test fails due to any altering in the hashes, then the DKIM test fails and your email is discarded.

DKIM is more complex than SPF as it carries more information. These public and private keys are meant to be updated regularly as part of your authentication practices. If not updated regularly, then your DKIM tests will fail.

Domain-based Message Authentication, Reporting and Conformance (DMARC)

Domain-based Message Authentication, Reporting and Conformance (DMARC) is interesting because it is not an email authentication method in the traditional sense.

DMARC is used along with SPF and DKIM to act as an additional security measure. It helps you set up a policy for failed checks and can generate email performance reports. This makes it the highest and most reliable measure for email authentication.

Here’s how it works:

  • When a DMARC-aligned email reaches your prospect’s inbox, an SPF and a DKIM check are performed as usual. Then, a domain alignment test is performed.
  • Simply put, this test matches the sender’s email address with the one stored in the SPF and DKIM records.
  • Once passed, the email reaches your prospect’s inbox.

You can adjust how lenient or stringent these checks are. Obviously, a more strict domain alignment test will not allow more emails to pass, while a lenient test will allow more to pass.

2. Sender Reputation

Sender Reputation is perhaps the most important part of deliverability.

Email sender reputation is a score that is assigned to your organization from your Internet Service Provider (ISP). A higher score indicates a higher chance to land in your prospects’ inboxes. If the score is too low, your emails will land in spam, other folders, or be rejected completely.

Sender reputation is based on several factors. We’ll examine the most important factors for you, the SDR.

An image illustrating the sender reputation.

Email engagement

Email engagement is the measure of how your prospects interact with your emails.

For example, when you send an email, a prospect may open it, read it, and interact with it in some way (by replying, clicking on links, or other ways depending on your CTA).

There are two types of engagements — positive and negative. Positive engagements are when your prospects read, reply, mark as important, or move your email to different folders. Negative engagements are not opening the mail, deleting it without reading it, or marking your email as spam.

Positive engagements improve your sender reputation while negative engagements hurt your sender reputation.

For an SDR, this measure is important because a lot of prospects may not open or read your initial cold outreach efforts. This can lead to your sender reputation being negatively affected, and can thus hurt your deliverability itself.

Don’t worry, though. We have a solution to this in the next section (and it’s not just cold email templates).

Domains and Blocklists

First, let’s explain your sender domain. Your email address should be with your organization’s domain or sub-domain.

For example, your email address should be or a related sending domain, like or

This is because it makes it easier for the user to recognize and therefore trust your email address and the company attached to it. For a job like sales, where trust is very important, this is an important matter that should not be overlooked.

If your mail comes from a domain that your prospects don’t recognize or trust, then there’s a high chance that they may mark you as spam, which might blacklist your domain.

A domain blacklist (also called a domain blocklist) is a list that allows ISPs to block emails from domains that typically send spam.

Your domain may also be blacklisted due to the gradual degradation of the reputation of the domain itself. This mostly happens because of sending many emails from a particular domain that have been classified as spam.

If your domain is blacklisted, you will need to delist your domain. This can be done by contacting the blacklists and requesting to be removed from them.

Here are the major blacklists that are widely used and that you should NOT be a part of:

  • Spamhaus
  • Spamcop
  • Invalument
  • Barracuda

3. Email List Management

Every SDR has an email list consisting of various prospects to reach out to.

Email list management is the process of upkeeping this list, specifically, to validate the list and remove inactive users from the list.

This process is critical for successful outreach, but it’s also important to maintain your deliverability.

From a technical standpoint, the most important part of email list management is to use an email verification or validation tool to ensure that your email list consists of valid email addresses.

When you have a huge email list, there are bound to be typos in the email address or there will be expired email addresses. If you send emails to these addresses, then your emails will bounce.

Bounce is when your emails cannot be delivered. You will receive an error message explaining why your email bounced, also called a Non-Delivery Report.

There are two types of bounces:

A hard bounce is a permanent problem. This can be caused because the email address doesn’t exist, or because the email server has been blocked.

A soft bounce is usually a temporary issue. This could be because the recipient mailbox is full, not configured correctly, inactive, or more.

A bounce negatively affects your deliverability. Emails that bounce are considered as undelivered.

Bounces hurt both your delivery rate and your deliverability rate, so combating this issue is of utmost importance. Validating your email lists is one way of preventing this issue.

4. Content

This section isn’t related to technical factors that affect your deliverability but is related to the contents of your email.

The algorithms that each email service provider (like Gmail, Outlook, Office 365, or GSuite) detects the contents of your email for spam as well. It checks everything — your header, footer, body copy, attachments, images, media, URLs, etc.

If you use overly sales-y language, words that the algorithm has detected to be spam words like “Buy now”, type in all caps, or use too many exclamation marks, there is a high chance your email will be marked as spam.

Therefore, it is important to draft your cold emails carefully to ensure that you don’t commit these mistakes. Try to write the email as though you were talking to that person. Try to avoid sending attachments and link tracking URLs.

The best solution is to personalize your emails with a sales engagement platform like Klenty.

To read more on deliverability dos and don’ts, check out this article.

How Do I Improve My Deliverability?

It’s critical that you land in prospects’ primary inboxes to capture their attention. While the many checks and balances set up by ISPs and email service providers protect users from spam, it often leads to a sales rep being unable to reach out to prospects. Luckily, there are several ways to improve your deliverability.

There are three main ways to improve your deliverability:

  • Email Warmup
  • Email Validation
  • Inbox Insights

These tools vary in their usages, but all contribute positively to your overall deliverability. Let’s explain each one.

1. Email Warmup

What is Email Warmup?

Email warmup is a way to establish and maintain a reputation for a new email account. It also helps increase the email sending limit. Email warmup is typically used for new email accounts.

Each service provider has a daily sending limit for new email accounts. For example, Google Workplace users have a daily email sending limit of 2000. This is set up in this way to dissuade spammers.

But for an SDR, sending that many emails is just a part of a day’s work. So, it’s important that you warmup your new email IDs to ensure that the algorithm doesn’t flag your email ID as spam.

How does Email Warmup Work?

Once you have a new email account, you may want to immediately start your outreach. However, the aforementioned daily sending limit is not applicable for new email accounts.

An email warmup process begins by sending a few emails from your new account, and then gradually increasing the number of emails sent every day.

These emails must be sent to known email addresses. These emails must have positive interactions, that is, opens, replies, and marked as not spam. This will improve your sender reputation and your deliverability, as you will be reaching primary inboxes.

Typically, this process takes 2-3 months to achieve the maximum sending limit and to attain a good reputation.

What are the benefits of Email Warmup?

1. Better sender reputation

Email warmup improves your sender reputation in many ways. Firstly, through the positive interactions that occur throughout the warmup, your sender reputation will increase. Secondly, a warmup establishes the authenticity of your email ID in the eyes of your email service providers, which are always on the lookout for spam.

2. Increased deliverability

Since email warmup is a slow and gradual process, your email ID will pass through the spam filters that check for bulk emails being sent out all at once. By passing through these filters, you avoid getting your email ID being marked as spam or even worse, get blocked entirely.

3. Focus on sales

Getting into prospect primary inboxes is critical for any cold email campaign. However, deliverability issues will throw a wrench in even the best campaigns. Warmup prevents right away, by ensuring that you land in primary inboxes owing to a strong sender reputation.

Additionally, not all cold emails have positive interactions. Having a warmup continuously running in the background provides your email ID with positive interactions to counteract any negative interactions. This means that even if prospects aren’t interacting with your emails, the warmup will, and thus your deliverability will remain intact.

Here are some Email Warmup tools you could try.

2. Email Validation

An image displaying Klenty's email validation feature.

What is Email Validation?

Once you’ve primed up your account for your outreach, the next step is to ensure your emails reach the right place.

That’s where email validation comes to play. Email validation is a process of verifying email addresses to remove any non-existent, invalid or risky addresses from your list.

According to a study, increasing the number of risky or invalid emails on your list by only 1% could lead to a 10% drop in your deliverability.

How does Email Validation work?

The verification process is a little more detailed than you’d think. Since bounces negatively affect your deliverability rate, email validation is crucial for anyone with long email lists. So, as a salesrep, this step is important.

During the verification process, you will check for:

  • Syntax issues like missing symbols
  • Verifying the recipients domain via DNS records to ensure the server able to receive emails at all
  • Ensuring that the recipient’s mailbox exists and can receive emails

What are the benefits of Email Validation?

1. Better Sender Reputation

If you repeatedly send emails to invalid or spammy email accounts, it could lead to your account being suspended. This also decreases your sender reputation, which will lead to lower deliverability on a whole.

Verifying your email lists ensures that your emails are sent to a valid and intended recipient. This greatly improves your deliverability.

2. Decreased bounce rates

When your emails are sent to risky or invalid addresses, your emails will be bounces. Hard and soft bounces negatively affect your deliverability greatly as this could lead to your email account being flagged as spam or blocked entirely by ISPs.

Verifying your email list removes these risky or invalid addresses from the list, thus reducing the chance of you accidentally reaching out to these accounts and negatively affecting your reputation. Decreasing your bounce rate will improve your deliverability greatly.

3. Increased accuracy of emails

By removing risky or invalid email addresses from your account, you are in turn reaching out to the right connections on your email list. Not only are you reducing bounce rates, but you are also indirectly improving your open and reply rates. These positive interactions not only help your sender reputation but, more importantly, improves the effectiveness of your email campaigns.

Check out these Email Validation tools to improve your deliverability.

3. Inbox Insights

An image displaying Klenty's inbox feature.

Before we discuss the merits of an Inbox Insights tool, let’s discuss the important of inbox placement.

What is Inbox Placement?

As mentioned earlier, emails that reach the prospect’s inbox is delivery. But, deliverability refers to the percentage of mails that reach the prospect’s primary inbox. This is called the inbox placement rate.

Inbox placement rate does not factor in emails that were undelivered, such as the case in soft or hard bounces.

This metric is crucial because it tells you where exactly you’re landing in your prospect’s inboxes. It will also give you an understanding of how healthy your inbox truly is. You will know why your open, response and engagement rates are low as well.

With this understanding, let’s move on to Inbox Insights.

What is Inbox Insights?

Put it simply, Inbox Insights is a diagnostic tool that helps you understand your inbox placement rate and your inbox health.

Working off the aforementioned inbox placement rate, Inbox Insights is a diagnostic tool that will give you clarity on where exactly your emails will land in prospect inboxes — in the primary inbox, promotions or social tab, or spam folder.

What are the benefits of an Inbox Insights tool?

1. Know exactly where you land

Since Inbox Insights tools use the inbox placement metrics, you will know exactly where your emails land. You will be able to view a percentage breakdown of your email placements, which will give you an insight into your deliverability.

2. Suggestions to improve deliverability

Once you’re aware of where you’re landing, you may want to improve your deliverability. A good Inbox Insights tool will recommend ways to improve your deliverability, from warmup to validation to which domains are currently blacklisting you. Then, you can take the appropriate action to improve your deliverability.

3. Detailed breakdown of deliverability

There are various technical details such as email validation and sender score that affect your deliverability. A good Inbox Insights tool will give you a clear idea of your authentication records (SPF, DKIM, DMARC), your sender score, any domains that have blacklisted your ID, and more. This will once again give you insight on how to improve your deliverability.

4. Email provider insights

Every email service provider follows different algorithms to determine deliverability. There is a difference between Gmail and Outlook’s algorithms, and they are constantly changing to combat spam. However, as an SDR using a particular provider and reaching out to various providers, it’s important to understand your deliverability within each recipient. Instead of worrying about these ever-changing algorithms, a good Inbox Insights tool will break down your deliverability with each of these recipients, so you can clearly view your deliverability within each provider.

For more tips to improve your deliverability, check out this blog.


While deliverability may be a highly technical concept, there are several tools to help you fix your deliverability. Klenty’s Email Shield is one such tool that solves all of your deliverability needs.

With this ultimate Deliverability Suite, you’ll be able to improve your reach, land in primary inboxes, and book more deals as a result. Email Shield is the one tool you’ll need to deliver them all.

Check out Klenty’s Email Shield today.

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