5 Ways to Improve Email Deliverability

This blog post explores how to improve email deliverability. We look at ways to check your email deliverability and ways to ensure your emails are reaching your user’s inbox.

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Communicating and connecting with your users via email is crucial in business. Being able to connect with your users via social platforms or email is important. One difference is that email has been around since the start of the Internet and will be a constant in our lives. This blog covers how to reach your users by showing how to improve email deliverability. We recently discussed improving email deliverability on our LiveStream Coding with Nylas:

What is email deliverability?

Email deliverability is a measure of the percentage of emails that successfully reach a recipient’s address. In other words, email deliverability is focused on emails that reach your users’ inboxes. Let’s look at factors that impact email deliverability next!

Email deliverability factors

Quite a few layers exist between your email and the end user. Let’s discuss email deliverability factors.

IP reputation

Email is passed through different layers like an ISP (internet service provider) and they check the IP address the email was sent to filter emails from IPs that have lower sending reputation scores. For example, receiving a complaint for an email sent or sending large volumes will impact your IP score.

Contact list quality

Ensuring quality contacts is important to ensure high email deliverability. For example, sending emails to spam traps (i.e. fake emails) created by email providers will impact your email deliverability.

Email schedule

Sending large volumes of emails is frowned upon by email providers. Sending large amounts of emails daily or all at once will reduce the chances your email will reach your users.

Email analytics

Understanding how your email is received by your users is important. The following are important to consider when measuring email analytics:

  • Open rates
  • Email bounce rate
  • Time spent reading
  • Click through rates

Email providers will measure these values to understand how your email is being received by their users, which will impact email deliverability.

Email content

Content is important when it comes to email. Personalizing your email is important to ensure it is well received by your users and is relevant to them. This will impact your email metrics and also impact email deliverability.

How to check email deliverability

Many free tools are available online to check email deliverability and learn more about areas to tackle for improving email deliverability. 

For the below tools all you need is to pass in your email and you receive a full report detailing where you may have issues with email deliverability:

In addition to using the above tools to check for email deliverability, consider tracking the following email engagement metrics to observe for any changes:

  • Email bounce rate is when emails are not being delivered to the sender
  • Email open rate is when the emails are opened by the sender

How to improve email deliverability

Let’s go over ways to improve email deliverability using Nylas.

1. Improve IP reputation

Using Nylas, you can take advantage of the Nylas Email API to send emails on the user’s behalf, and furthermore, the user’s IP addresses. This is an alternative to using a transactional email service provider.

Here is a code sample of sending an email on your user’s behalf:

# {{url}} is the Nylas API endpoint
curl --location -g --request POST '{{url}}/send' \\
--header 'Content-Type: application/json' \\
# {{access_token}} is the user's access token
--header 'Authorization: Bearer {{access_token}}' \\
--data-raw '{
    "body" : "Thanks for visiting, here are your order details.",
    "subject": "We're processing your order W12408221",
    "to": [
            "name": "{{name}}",
            "email": "{{exchange_email}}"

2. Improve contact list quality

Using the Nylas Email API, you can follow up with re-confirmation or double opt-in emails to avoid possible spam traps that will impact your email deliverability. It’s also worth considering completing fraudulent checks for users before sending the email, such as scanning their IP or email against known lists of bad actors. You can also add your application email to your user’s contact list to be considered a safe sender using the Nylas Contact API.

Here is an code sample of adding your application to your user’s contacts:

# {{url}} is the Nylas API endpoint
curl --location -g --request POST '{{url}}/contacts' \\
--header 'Content-Type: application/json' \\
# {{access_token}} is the user's access token
--header 'Authorization: Bearer {{access_token}}' \\
--data-raw '{
  "emails": [{
  	"type": "Nylas",
  	"email": "devrel@nylas.com"

3. Improve email schedule

Using the Nylas Email API, you can decide when to send the emails. You can call our Email API at your own preferred time/day to improve email deliverability.

Also, you can decide how frequently to send out multiple emails to many recipients by spacing them out and calling the Email API at a certain frequency, like every 30s or sending an email once a minute.

4. Improve email analytics

Using our Nylas Email API and with a connected user account, you can check and learn more about email engagement. So learning about if the email is unread, or starred is possible using the Nylas Email API.

Another area to consider is tracking if emails are being delivered to the recipient. So if you start receiving error codes using the Nylas Email API, this may be a sign that emails are bouncing and you should consider pausing sending emails for a period of time before restarting.

Here is a code sample of retrieving a message and a sample response that contains properties starred and unread:

# {{url}} is the Nylas API endpoint
curl --location --request GET '{{url}}' \\
# {{access_token}} is the user's access token
--header 'Authorization: Bearer {{access_token}}'

# API Response
        "account_id": "{{account_id}}",
        "bcc": [],
        "body": "Order details...",
        "cc": [],
        "date": 1673852731,
        "events": [],
        "files": [],
        "from": [
                "email": "{{email}",
                "name": "{{name}"
        "id": "{{message_id}}",
        "labels": [
                "display_name": "Category Updates",
                "id": "a0sdwue0287lhsk9itxz2q377",
                "name": "updates"
                "display_name": "Inbox",
                "id": "49eh9pixzuj18pbe78lntkbf4",
                "name": "inbox"
        "object": "message",
        "starred": false,
        "subject": "Insights Digest - Week of Jan 9 for Nylas",
        "to": [
                "email": "devrel@nylas.com",
                "name": "Nylas"
        "unread": true

5. Email content

When sending an email, try to personalize the content as much as possible. Mail merge is where you combine data with information such as a person’s name and previous transactions with an email to create a personalized message. Using mail merge and the Nylas Email API you can send personalized messages to users that get more engagement and improve your email deliverability.

How to ensure email deliverability

You can use the Nylas Email API to ensure email deliverability by considering the following:

  • Aim for working with a solid IP reputation score by considering using your user’s email address to send emails
  • Ensure your contact list is of high quality by completing double opt-in and scanning for bad actors
  • Schedule emails to send at specific times of day at a reasonable frequency
  • Understand email engagement by tracking email send errors and email open rates
  • Consider using mail merge to personalize emails to improve email engagement

Build with Nylas!

Continue building with Nylas and learn more by visiting the Nylas Email API overview. Sign up here if you need to create a Nylas account for free!

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