What is Email Delivery?

Email delivery is a fast and reliable service for sending emails through a Simple Mail Transfer Protocol (SMTP) relay. Email deliverability is a metric that measures the percentage of delivered emails, or emails that successfully reach a recipient’s email address. Implementing email delivery functionality into your application helps you scale up email infrastructure and increase email deliverability.

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Email delivery plays a critical role in software communications. An email delivery service lets applications send programmatic emails for core communications such as receipts, alerts, identity verification, password resets, sales outreach, customer support, and more. 

Any cloud-based application that sends emails and needs to reach the user’s inbox with high deliverability rates should use email delivery. If you’re a developer thinking about adding email delivery functionality to your application, read on to learn more about how it works and what best practices to be aware of. 

Why is email delivery important? 

Email deliverability is essential for any business and here is why:

Email delivery builds trust and reputation

Poor email deliverability can harm a brand or platform’s reputation. If emails end up in the spam folder, recipients may view the brand as untrustworthy. Like a reliable mail carrier – if they deliver physical mail accurately and on time, their service is trustworthy.

Email delivery ensures effective communication

Email is used for essential communications like transaction confirmations, sales outreach, customer support, and other important updates. If these emails don’t reach the inbox, it can disrupt the user experience. Imagine missing an urgent flight update because the email went to spam.

Email delivery maximizes ROI

Email marketing has one of the highest returns on investment (ROI) among digital marketing channels. However, this ROI is compromised if emails do not reach the inbox. It’s like shooting arrows in the dark; you can’t hit the target if you can’t see it.

Compliance and legal considerations

Certain industries have regulations requiring timely and accurate email delivery. Failure to meet these can result in legal consequences. For instance, financial institutions must send timely statements to clients; failure to do so can result in penalties.

Enhances customer engagement

Emails that reach the inbox have a higher chance of being opened, read, and acted upon. This increases customer engagement, which is vital for building long-term relationships. 

How does email delivery work? 

Most emails are sent using SMTP. This protocol can both send and receive emails, but it often defers to IMAP or POP3 for queuing incoming messages. Systems like Gmail, Microsoft Outlook, and Apple Mail have their own mail transfer protocols when using their own servers. 

The basic components involved in email delivery are:

  • Mail user agent (MUA): the client software with which the user sends and receives email
  • Mail transfer agent (MTA): the software that routes messages from the sender’s system to the receiver’s system 
  • Mail delivery agent (MDA): the server software that delivers the email to the user’s MUA 

Another essential component of email delivery is email headers. Evaluating headers can provide information about errors that may have the potential to prevent delivery. Email headers contain details about who sent and received a message and whether the message passed through a server. This data helps identify deliverability problems. 

Headers are also a great way to identify the source of an email, helping protect against phishing and spam. The email header gives the tracking route of the email: information on which servers, ISPs, and email platforms the message has been sent through. It helps identify where the email was at risk of being compromised.

Why use an email API for email delivery? 

Using an email API enables developers to automate email delivery, reducing the chances of message failure. 

One of the main advantages of using an email API is improving email deliverability, ensuring every email reaches the recipient’s inbox. The deliverability rate is high when the number of emails sent is close to or equal to the number of emails reaching the recipients’ inboxes. Conversely, emails that bounce or are sent to spam reduce the deliverability rate. 

How can developers improve email deliverability? Implementing an email API allows developers to achieve near-perfect deliverability by managing the entire inbox within the application. 

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Challenges of email delivery configuration

1. Wrong DNS records 

Setting up DNS records (MX, SPF, DKIM, and DMARC) to improve deliverability is a common practice. When the user sends an email, the recipient’s server scans the corresponding SPF, DKIM, and DMARC records to validate the DNS records and sends an alert if any discrepancies exist. For instance, if there is a problem with the recipient’s server or it doesn’t match the DNS records, it may return an SMTP error code of 550 or 554.  

2. Configuring reverse DNS (rDNS) for IP reputation management

Reverse DNS is an additional way of verifying the sender, in which the DNS lookup finds the domain name based on the IP address. Reverse DNS allows anyone to view the source of the email transaction, which is why illegitimate senders usually don’t have reverse DNS records. Configuring reverse DNS validation can help build the IP’s reputation as a legitimate address.

3. Managing email queues and ensuring timely delivery 

Some protocols are not efficient enough to manage email queuing. SMTP email queues, for instance, will temporarily store emails and send them one at a time. While this usually ensures the emails will not bounce, the queue may get stuck when the server needs to handle high email volumes. An email API may help with changes in email volume and scalability. 

4. Implementing email tracking and analytics for insights 

To ensure deliverability, developers should implement thorough tracking and analytics. The Nylas API offers tracking of multiple actions happening to messages, such as if the message was opened or the thread replied to.

5. Monitoring and analyzing email deliverability metrics 

Key metrics can reveal whether emails are reaching the inbox without bouncing or being flagged as spam. Monitoring and analyzing these is critical to having a complete picture of what is happening and why. These metrics may include the delivery rate, the open rate, the click rate, the bounce rate, and the spam rate. 

6. Implementing feedback loops and handling bounce messages 

Part of email delivery best practices is managing bounced emails and spam complaints. Ignoring these can result in a bad sender reputation and even blacklisting an IP.  Feedback loop emails are generated when a recipient flags the message as spam. Implementing feedback and bounce loops can help reduce spam complaints. These services help identify factors causing the emails to bounce or be marked as spam. Some email providers and APIs have these features incorporated. 

Best practices to increase email deliverability 

Authentication and email validation are some of the best practices that can improve the email deliverability rate. Here are more:

Use an API to deliver email

An API provides convenience and automation to ensure deliverability optimization. Adding the Nylas Email API to your application streamlines the tracking, monitoring, and management of email delivery, effectively increasing your deliverability rate. 

Scale up with proper IP allocation 

Keep a robust email infrastructure that allows the addition of dedicated IP addresses. Warming up the IP address will prevent it from being blocked. 

Optimize the opt-in process 

One of the main factors that can affect deliverability is how the application collects email addresses. An optimized process ensures that only users who agree to receive emails are added to the list, preventing the emails from being marked as spam. 

Implementing double opt-in and unsubscribe mechanisms are two practices that can help. Double opt-in requires two verifications for the user, ensuring they agree to be added to the email list. 

Use a retry policy 

Sometimes, despite the best intentions, there are email delivery failures. There can be a loss of network connectivity, timeouts, or temporary unavailability. Applications are sensitive to transient faults so that email deliverability can be affected. A built-in retry mechanism monitors a request, and if it detects failure, it automatically sends a repeat. Usually, the system retries several times, such as in the case of soft bounces due to ISPs’ difficulty delivering mail. 

How do appointment scheduling APIs work? 

The API receives requests to perform scheduling functions, like retrieving a list of available appointment times or creating a new appointment. APIs typically use Representational State Transfer (REST) protocols or Simple Object Access Protocol (SOAP) to exchange data between the scheduling platform and a developer’s software. The process usually goes like this: 

  • Step 1: The user opens the appointment scheduling API in your application. 
  • Step 2: The API shows a calendar with available appointment times. 
  • Step 3: When the user chooses an appointment, it gets added to all relevant calendars.

Build your future with Nylas Scheduler

The Nylas Scheduler allows you to embed automated scheduling features directly into your application. You can quickly build and customize a front-end scheduler with a pre-built front-end widget. The scheduler will be unique to your application. With Nylas, you can add easy-to-set-up scheduling features to your app without writing custom code, such as automated workflows that will save users hours a week in scheduling. Embedding scheduling in your application streamlines scheduling.

One Fortune 500 e-commerce company wasted 6+ months, 40+ engineers, and $100,000+ building email-powered functionality. With Nylas, the team deployed a solution for millions of users in two sprints with just four engineers.

You don’t have to compromise customization to have automated scheduling because you can build a tailored, front-end scheduler in your app, unique to your brand. By choosing the right software for your business and implementing it effectively, you can streamline your operations and provide a seamless experience for your staff and clients. 

Frequently asked questions

What is email deliverability?

Email deliverability refers to the number of emails that effectively reach recipient inboxes compared to the number of emails sent. Some people distinguish between delivery and deliverability, with delivery referring to whether the receiver accepts or rejects the email and deliverability referring to where the message ends up in the inbox or spam folder. 

Average industry deliverability rates are far too low to ensure proper sending. With Nylas, you can build email features your users can trust with industry-leading 99.6% deliverability. Learn more about improving your email deliverability here and ensure your emails reach your user’s inbox.

Who should use email delivery?

Organizations and developers that want to add email capabilities to their applications. An email delivery API improves tracking and reporting and automates and optimizes email deliverability. 

How do I improve email delivery?

Use an email API and apply best practices such as authenticating the email domain, allocating IP addresses properly, building IP reputation, and refining the opt-in process to maximize email delivery. 

How do I fix email deliverability issues?

First, ensure the email infrastructure is solid and the SPF and DKIM are valid. Monitor and identify the causes of the high bounce and spam rates. Test the email API — one easy way to do this is to sign up for Nylas and test it in the sandbox. 

What’s a transactional email service?

Transactional emails are sent to users after a commercial transaction or a sign-up for a service. Transactional email services, such as a welcome email or password reset, are usually non-promotional and sent automatically after an event or interaction between the user and the application or web app.

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Additional Resources

10 Best Email APIs in 2023
10+ Best Email APIs in 2023 for Developers [Free & Paid]
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5 Ways to Improve Email Deliverability
How to Create a Mail Merge Template with Ruby

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