What is Email Delivery?

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. 

Email delivery vs. email deliverability

While email delivery measures the number of emails successfully delivered to the recipient’s email address, email deliverability is a metric that considers the percentage of emails that successfully reach a recipient’s email inbox. 

Email deliverability is an important component of email delivery as internet service providers (ISPs) have been increasingly implementing strict email filtering to combat junk mail reaching user inboxes. Tests across 15 email service providers (ESPs) revealed an average deliverability rate of 83.1%, meaning nearly 1 in 6 marketing emails never reach their recipients’ inboxes.

Therefore, high email deliverability is essential to ensure your businesses’ crucial communications land in customers’ inboxes, not spam folders, social updates, or other rarely checked locations.

Read more about how to improve email deliverability here.

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.

What affects email delivery?

Several factors can influence the success of an email being accepted by the recipient’s server. Let’s briefly dive into the top components that impact email delivery.

• Sender IP reputation: ISPs assign a sender reputation score to your IP address, reflecting your past email behavior. This score heavily factors into whether your emails are trustworthy and belong in recipients inboxes.
• Email authentication: Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM) act as identification tools for ESPs. These protocols help verify if an email is legitimate and truly originates from the sender’s domain.
• Email content: Tailoring relevant content for individual recipients directly impacts email deliverability and engagement. Emails with spam trigger words or irrelevant content risk being flagged and filtered by ESPs.
• Contact list quality: Maintaining a clean and engaged contact list is crucial for email delivery. Verified, opted-in recipients who actively interact with your email communications signal legitimacy to ISPs. 
• Email schedule: Sending a large volume of emails in a short burst can trigger spam filters with ESPs. Strategically planning your email cadence and timing is crucial for ensuring inbox placement.

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 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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Top 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. 

The role of email verification in email deliverability

Improving email deliverability doesn’t just involve ensuring the emails reach the user’s inbox — it also means taking measures to prevent spam filters from marking the emails as spam. 

Email authentication allows the internet provider to verify that the emails sent are legitimate. Authenticating and validating emails helps maintain the sender’s reputation and secure the IPs as valid.

Why is authentication important for deliverability? 

Because authentication can track the sender’s reputation, it lowers the risk of spam filters rejecting the email. Authentication technology offers a way to prove the email comes from a legitimate sender and is not forged. An email is usually blocked and won’t reach the inbox if it doesn’t pass authentication checks. 

Enabling Sender Policy Framework (SPF) and Domain Keys Identified Mail (DKIM) also helps prevent spoofing — an unauthorized user taking control of the email domain — negatively impacting deliverability. 

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 Nylas Email API improves email delivery

The Nylas Email API lets users send messages from their email address, unlike transactional APIs that rely on a shared, third-party IP. With Nylas, developers can build send and receive capabilities with near-100% email deliverability. The Nylas Email API also offers full CRUD capabilities, support for email threading, and compliance with strict security regulations. 
Request a demo to discover the capabilities of Nylas Email API for yourself. If you are ready to start building, request your free API key today.