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21 Email deliverability best practices you must follow in 2023

18 min read
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Despite the introduction of instant messaging and other mediums of online communication, email stands apart as being the most preferred channel for business communication.

According to recent data, 306.4 billion emails are sent and received every day. Having said that, 81% of SMBs use email as the primary source of customer acquisition.

But what about email deliverability?

Of the 306.4 billion emails sent every day, 50% of the emails land in spam.

This means 50% of the emails sent never reach the recipient as intended. Poor email deliverability massively impacts sales and marketing efforts.

It invariably results in a drop in productivity levels and consequently, revenue losses.

With this article, we will explore all the best practices to avoid your emails landing in spam. Following all of these will give you the best chance at getting your emails delivered to your recipient’s primary folder.

What is email deliverability?

Email deliverability is the ability to deliver the email to the recipient’s mailbox.

This is not as simple as it might seem.

There is an entire process an email has to go through before reaching the recipient’s inbox. The email has to move through different filters designed by various email service providers, like spam filters, content filters, etc.

When it’s all done, the email lands in one of the recipients’ inbox folders, like spam, primary, promotions, updates, etc.

Why is email deliverability important?

Email deliverability is important for two reasons:

  • Get your conversions done:
    Everyone sends their emails with a purpose. They want their users to read the email and take action. But if the email doesn’t get delivered correctly, it will thoroughly affect the end goal.
  • You don’t want to be a spammer: 
    No one wants to be a spammer. Everyone wants to enjoy the freedom of reaching directly to the inbox rather than being dumped in the spam. But if we don’t follow the best practices of sending mass emails, you will be labeled as a spammer soon. If people start marking you as spam, it becomes a critical email deliverability issue. 

To maximize the efficiency of an email campaign(sequence), you need to get it right from the moment you start creating your plans.

Let’s dive deep and understand what all goes into improving your email deliverability. 

Email deliverability best practices


Now that we have seen the importance of email deliverability for your sales and marketing outreach. Let’s explore the best practices to set up your emails for maximum deliverability.

Step 1: Authentication
Step 2: Sender reputation
Step 3: Email content
Step 4: User engagement

1. Authentication

Every day we come across many mass email senders who are facing issues with email deliverability. They explain that their new account gets blocked even though they send a mass email to a small list of 100 recipients.

Yeah! It’s true; it happens, the first thing a mass email sender must know is to authenticate their email account.

Authenticating your email account is like providing a driving license to it for moving ahead on the road to the receiver. 

There are four types of authentications required to send mass email without blocking your email account and landing straight to the recipient’s inbox.

  1. SPF
  2. DKIM
  3. DMARC
  4. Custom Domain

i. SPF(Sender Policy Framework)

SPF is an email authentication protocol that allows the admin of the domain to define the list of mailing servers used from the domain.

SPF creates a record in your DNS (Domain Name System), which lists down all the servers that are authorized to send emails on behalf of a domain. The record also specifies how recipients are supposed to handle emails that are sent from unauthorized servers.

Whenever a sender sends an email from an SPF authorized domain, the recipient’s ESP checks the SPF authentication and provides a clean chit to the sender’s domain.

ii. DKIM(Domain Keys Identified Mail)

DKIM is another email authentication process designed to detect email spoofing.

DKIM provides an identical digital signature with your DNS records, which helps the sender’s ESP to verify that the email it has received is from an authorized source.

Adding the DKIM records in the DNS boosts your email productivity and helps you from staying away from many major email scams.

  • DMARC(Domain-based Message Authentication, Reporting & Conformance)

DMARC is not a must-have authentication process but a good-to-have authentication process to improve email deliverability.  

DMARC records use your SPF and DKIM records to assure the receiver’s ESP that no fraudulent activities are associated with the email.

Sometimes the Internet service providers also restrict some IP addresses or domain servers. In these cases, the DMARC records come to the rescue and make your email go through it.

iii. TLS

TLS is a form of protocol that works to provide security for the data transferred between two entities.

It keeps the information safe from eavesdroppers and hackers to ensure the information stays only between the two entities (the sender and the receiver). 

iv. Custom domain

Adding a custom domain is a trick to improve email deliverability.

Also, tracking links in your email body pulls your emails to the spam filter because the ESPs usually blacklist the tracking links.

Providing a custom domain changes the original tracking domain with your customized domain, which is safe to use and not blacklisted by any email service providers.

Usually, email automation tools like Saleshandy allow you to add a custom domain to your links to improve your email deliverability.

2. Sender reputation

Sender reputation is a score decided by various email service providers according to your domain score and IP address.

The more the score, the better is the email deliverability. We are describing all the factors below that help a sender to increase his sender’s reputation.

i. Warm up your email account

Although after authentication, you have received a license to drive your emails to the recipient’s inbox. But it’s never suggested to send huge email campaigns(sequences) from a new email account.

You have to start slow and grow gradually. 

If you send a mass email campaign(sequence) at the first take, your account might come under the vigilance of your email service provider, and this can affect your email deliverability. Sometimes this might end with permanently blocking your account.

You need to start by sending individual emails and creating conversations. You should follow this practice for a few days and gradually increase your number.

Email warmup helps in increasing your sender reputation score and makes your account healthy for email campaigns(sequences). You can use the Saleshandy email warm up feature to easily warm up your email account. Just follow the below steps to warm up your account using Saleshandy:

Step 1: Sign-up to Saleshandy
Step 2: Connect your email account
Step 3: Step 3: Navigate to the Email Warm-up tab
Step 4: Turn on the toggle for the email account you want to enable warm-up for

ii. Maintain sending quota

Even though you are allowed to send bulk emails after authentication and warmup, you should keep track of how many emails you are sending in a day.

If you pull out a long list of recipients and start sending emails without keeping a count, your emails might start getting blocked.

You should never exceed your email quota. If you exceed your email quota regularly, your email service provider starts keeping an eye on your activities and might get your account blocked temporarily or permanently.

You need to make it a practice to not exceed the email sending quota.

iii. Stay aware of email blacklists

Email blacklists are the list of IP addresses and domains that are suspected of sending spam emails.

It is a real time database that decides which emails are valid and which all are spam. Refer to the tools towards the end of the article to know more about email blacklist checking tools.

There are two types of email blacklists:

  • Domain based:
    These are the list of domains that frequently misuse the domain by sending spam or doing any phishing activities.
  • IP address based:
    These are the list of IP addresses or networks which are frequently used to send spam or abusive content.

You should continuously check your domain and IP address. If it is blacklisted, you need to start warming up your domain once again and make a fresh start.

iv. Feedback loop

Oftentimes, email service providers enable senders to collect feedback from unsubscribing recipients, by redirecting them to complete short surveys or forms.

This enables you in building a feedback loop that helps you keep in touch with your users’ needs.

When a recipient doesn’t want to stay subscribed to a particular sender, they can write feedback to the sender with the reason, creating meaningful engagement.

In the long run, the feedback loop helps in email deliverability.  This way, the sender can also maintain a cleaner, more valuable list of recipients.

Feedback email

v. Email list should be verified

Getting a list of recipients is not a difficult task. Email addresses of your recipients can often be invalid or expired.

So, it is always suggested to verify the subscriber list with a verification tool. Verified email lists decrease your bounce rate, increase your email deliverability and also your sender reputation score.

Usually, after verifying your recipient’s list through any tool, it segments your recipient’s list into 3 types: Valid, Risky, and Invalid.

Valid: These are the verified contacts and are safe to send.

Risky: These are the existing contacts but are not safe to send as those accounts lack engagements.

Invalid: These are the non-existing or expired contacts, and we suggest against sending emails to them. The emails sent to these addresses are known to bounce.

vi. Stay away from email bounces

No one wants their emails to get bounced, but still, it happens to 9.94% of business emails.

Bounced emails can be equivalent to lost opportunities despite the efforts. Apart from that, frequent bounces are likely to make a sender’s domain land on a blacklist, and/or blocked by the email service provider.

There are 2 types of bounces –

  • Hard bounce:
    Hard bounce occurs when your recipient’s email address is not existing, has expired, or the domain is invalid. This is a permanent bounce and you can never send an email to that email address. You need to remove those email addresses from your recipient’s list. 
Address not found email
  • Soft bounce:
    Soft bounce occurs if the recipient’s inbox is full, or your email file size is too large or any other temporary issue. These bounces are for a short time duration, but if you are unable to send emails to these email addresses after multiple tries, you need to remove the recipient from your list.
Delivery incomplete email

3. Email content

The email content is the primary factor that decides whether your email will land in the recipient’s inbox or spam. Follow all the best practices mentioned below to create good content for excellent email deliverability.

i. Subject line

The subject line is the first thing the recipient sees when they receive the email. 69% of recipients report email as spam based on the subject line.

Spam filters also do the same thing. If the subject line contains spammy keywords or anything that is not relevant to the recipient, then it is more prone to get filtered into the spam folder either through algorithmic filters or by the recipient.

Ultimately this is going to affect your email deliverability.

ii. Spam triggering words

It’s crucial to restrict spammy words in both the subject line as well as the email body.

Various email service providers keep updating this list of spammy keywords in their algorithms to filter your emails. Even a single spammy keyword might affect your email deliverability to a high extreme.

iii. Text to HTML ratio

The visual content produces the best conversion, but it is likely to hurt your email deliverability.

An email with too much HTML content looks spammy but at the same time, readers don’t prefer plain text emails. So, to have the most suitable balance of both, the best practice is to maintain a 60:40 text to HTML ratio.

iv. Links

Using links in emails is essential for conversions. However, using too many links in a single email pulls the attention of the ESP and makes your email hit the spam folder.

It’s very dangerous as it affects your sender reputation score and email deliverability. 

Other additional links include email tracking links. The tracking link is usually blacklisted by various ESPs, which has a direct impact on your email deliverability rate.

v. Personalization

Personalized emails tend to have 29% higher open rates than others. That’s obvious; since everyone loves to be addressed personally.

Furthermore, increased email open rates eventually improve your email deliverability and your conversions.

Using a cold emailing tool like Saleshandy helps the sender to add personalized merge tags and hyper-personalize the email using Spintax. This improves your email deliverability and brings your email goals much closer.

Personalize your email using Saleshandy

vi. Text formatting and color

Text formatting plays a crucial role in enhancing user engagement. 

Writing a subject line in all CAPS triggers spam filters. It’s recommended to write as if you are sending a message to your friend.

Also, while composing the email, don’t use multiple colors as it is a bad practice; it decreases your email deliverability.

vii. Mobile-friendly design

One more factor to consider for enhancing the user experience on your page is to have a mobile-friendly site.

Google’s US organic mobile search traffic is 63%, so if your site doesn’t load properly on their device, they’re most likely to leave. You’re not only losing engagement but a good amount of traffic from your site.

4. User engagement

 If your email has great deliverability, your recipients will still mark your emails as spam if the email content is not relevant to them.

So, it is very important to create engagement around your emails to avoid getting reported as spam. Refer to the following best practices to generate more engagement.

i. Segment your email lists

Segmenting the email list is one of the best practices to be followed.

You need to categorize your recipient list according to the types of prospects.

After that, you should send relevant emails to your recipients. It might be possible that the email content you send is relevant to a marketer but not to a recruiter. In such cases, a recruiter might mark your email as spam, which you don’t want.

It is also suggested to remove recipients from your segmented list if they are not replying to your emails and follow-ups(steps).

If your emails are irrelevant, then they might be spamming it. Ultimately you want to maintain your sender reputation score and improve email deliverability.

ii. Add an unsubscribe link

Adding an unsubscribe link in your email campaign(sequence) is mandatory as per CAN-SPAM laws. If a recipient wants to opt out from your emails, they look for an unsubscribe link.

If they don’t find one, they’re highly likely to report your email as spam.

Getting spam reports is more detrimental than getting unsubscribed. An increase in spam reports is going to directly decrease your email deliverability and domain score.

Add an unsubscribe link

iii. Use a persuasive subject line

Using a persuasive subject line tempts the customer to open the email and have a look at it. It is a beneficial psychological factor that affects your email deliverability.

Subject lines like “Here’s a quick way to start selling your product” create a temptation in the recipient’s mind and make them open the email.

Deceptive email subject lines like adding “FWD:” or “RE:” at the beginning of the subject line forces the sender to mark spam even if he reads the content.

iv. Email seed list

An email seed list is a group of emails that are used to test your email deliverability before running the actual mass email campaign(sequence).

This particular list contains test email addresses of different ESPs through which a sender can know all about the vulnerability of his email content towards different ESPs.

The email seed list can help a sender to plan accordingly.

Email deliverability testing tools

Before sending a mass email campaign(sequence), we need to test email deliverability at every step for knowing the email sender score and your domain health.

We are listing some of the best tools that are going to be useful for testing email deliverability.



Zerobounce provides an email deliverability toolkit to help you improve your email performance.

They have two main tools to test your deliverability before sending.

First, the email server tester detects any potential issues with your email server, so you can fix them ahead of launching your campaign(sequence).

Then, the inbox placement tester gives you an idea of where your email will land (inbox or spam). This can be your one suite solution for testing your emails before sending them.

Mail Tester


Mail-Tester is a free tool to check all the detailed aspects associated with your email content and domain.

You need to send an email with your content to an identical email id provided by mail-tester and mail-tester will provide all the details of your email contents and authentications.



Glockapps is a similar tool as Mail-tester but with many advanced features. You can check whether your emails are dropping in the inbox or the spam box for different email service providers.

With the premium plan of the Glockapps, you can do a complete email deliverability test and get a report of email subject line, email body content, authentications, and blacklists.



Mxtoolbox is a popular tool used by many email marketers to improve their email deliverability.

This tool provides all types of tests regarding your domain health and DNS. Mxtoolbox is also used widely for testing the blacklist score as it shows relevant results.

DKIM Validator


DKIM Validator is a straightforward and free tool to check your authentication and improve your email deliverability.

With DKIM Validator, you can check if your SPF and DKIM are correctly working or not. Along with that, it can also show the spam score of your email content.



SendCheckIt is a subject line testing tool, which helps you to check the spam score of the subject line and also provides simplified suggestions on how to improve your subject line for better email deliverability.

Get here: 11 Email Deliverability Tools to Land In The Primary Inbox



ISnotSPAM is used to check the spam content in your email body.

Just send an email to the identical email address provided by ISnotSPAM, and you can see the spam score and all the details about improving your content.

It lists down all the checklists that usually get hit into the spam filter, from the email content side.


Email deliverability best practices


Getting your emails delivered to the right folder of the right person at the right time is nothing less than an achievement.

To get the best results, make sure to follow all the best practices we listed above before you start sending your campaigns(sequences). This will build your sender reputation, increase your domain reputation, and maximize email deliverability.


1. What is email deliverability?

The ability to deliver an email to the recipient’s mailbox is known as email deliverability. In this process, the email has to go through different filters designed by various email service providers, like spam filters, content filters, etc. to reach the recipient’s inbox.

2. What affects email deliverability?

Factors like the content of your email, links in the email, authentication factors, domain reputation, and user engagement affect the email deliverability. 

3. How do I check my email deliverability?

You can check the email deliverability using tools like Mail-Tester, Glockapps, Mx toolbox and DKIMValidator.


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