Email deliverability best practice

Posted in Notes on 5 May 2024

Email deliverability refers to the ability of an email to successfully reach the recipient's inbox, rather than being marked as spam or bouncing back.

High email deliverability ensures that emails sent by an organisation are received by the intended recipients. Several factors influence email deliverability, including the sender’s reputation, email content, recipient engagement and technical configurations.

Key factors affecting email deliverability

Sender reputation

Sender reputation is a combination of factors that email servers use to determine the reliability of the email sender. This will typically include the reputation of the IP address from which the email is sent. Using a dedicated IP address can help maintain control over your sending reputation. The reputation of the sending domain itself will also be used. The domain should also be consistent, high-quality email practices improve domain reputation over time.

Authentication protocols

Authentication protocols verify the email’s sender is connected with the domain name used to send the message.

  • SPF (Sender Policy Framework): Allows the domain owner to specify which mail servers are permitted to send email on behalf of the domain.
  • DKIM (DomainKeys Identified Mail): Adds a digital signature to emails, allowing the recipient to verify that the email was indeed sent from the claimed domain and has not been altered.
  • DMARC (Domain-based Message Authentication, Reporting & Conformance): Works with SPF and DKIM to provide a way for email domain owners to protect their domain from unauthorised use.

Content quality and recipient engagement

  • Avoid Spammy Content: Avoid using excessive exclamation marks, all caps and trigger words commonly associated with spam.
  • Personalisation: Personalised content tends to have better engagement rates.
  • Clear Unsubscribe Option: Including an easy way to unsubscribe can reduce the chances of your emails being marked as spam.
  • Open Rates and Click Rates: High engagement rates signal to email service providers (ESPs) that your emails are valuable.
  • Low Bounce Rates: Ensure your email list is clean and up-to-date to avoid sending emails to invalid addresses.

Technical setup

  • Proper Email Headers: Ensure correct configuration of email headers, including “From,” “Reply-To,” and subject lines.
  • HTML and Text Versions: Providing both HTML and plain text versions of emails can improve deliverability.

Sending Email

Use a Reputable Email Service Provider (ESP) — Services like SendGrid, Mailgun, Amazon SES, or similar providers handle many of the complexities of email deliverability. They offer features like detailed analytics, reputation management and compliance with authentication protocols.

Implement Authentication Protocols:

  • SPF: Publish an SPF record in your domain’s DNS settings.
  • DKIM: Configure DKIM by generating a public-private key pair and publishing the public key in your DNS settings.
  • DMARC: Set up a DMARC record to specify how your emails should be handled if they fail SPF or DKIM checks.

Monitor Email Metrics — Continually monitor and track bounce rates, open rates, click rates and spam complaints. Use this data to adjust and improve your email strategies.

Maintain a Clean Email List — Regularly clean your email list to remove invalid or unengaged email addresses. Use double opt-in methods to ensure the validity of email addresses.

Optimise Email Content — Use responsive design to ensure emails display correctly on all devices. Avoid spammy content and ensure your email’s subject line and body are relevant and engaging.

Test Before Sending — Use tools to test your emails for spam triggers and rendering issues before sending them to your entire list.


Example Workflow

This is an example workflow for anyone senging transactional emails or newsletters to uses from their web application or ecommerce store

  1. Choose an ESP:
    • Sign up for an account with a reputable email service provider like SendGrid, Mailgun, or Amazon SES.
    • Alternatively, your hosting company may provide this as part of their service.
  2. Configure Your Domain:
    • Set up SPF, DKIM and DMARC records in your domain’s DNS settings as per the ESP’s guidelines.
  3. Integrate ESP with Your Web Application:
    • Use the ESP’s API or SMTP relay to send emails. Most ESPs provide SDKs for easy integration with various programming languages.
  4. Compose and Send Emails:
    • Create email templates and use the ESP’s API to send personalised emails.
    • Keep generic emails to a minimum, customised content will work best.
  5. Monitor and Optimise:
    • Continuously monitor email performance metrics provided by the ESP and optimize your email campaigns accordingly.

By following these best practices, web applications can ensure higher email deliverability, leading to better engagement and communication with users.

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