What is Email API Security?

Email API security is the measures you take to protect email communications through an application programming interface (API).Thus, you can use an API to protect email data's confidentiality, integrity, and availability.

Safeguard Your Users’ Data With a Secure Email API

Despite the popularity of chats and messenger applications, email is still the most popular digital communications channel. Almost all businesses and consumers use email for marketing and customer experience purposes. In today’s interconnected world, where email remains such a critical tool, ensuring its security and integrity is critical.  

The challenge of email security is compounded because so many cybersecurity threats target email accounts. As developers, we are responsible for implementing robust measures to protect sensitive information exchanged via email. Let’s explore the concept of API email security, its importance, and how it empowers developers to safeguard email communications.

Why is email API security important?

Emails are a convenient and popular attack vector for cybercriminals. As such, ensuring your email API is secure is essential to minimize the following security risks: 

Unauthorized access to email data

Protecting sensitive information via email is one of the first steps to preventing data breaches and maintaining privacy. A secure email API guards data confidentiality by implementing encryption protocols in transit and at rest. These measures prevent unauthorized people and entities from accessing sensitive email content.  

Email spoofing and phishing attacks

Just one phishing attack can wreak havoc across an organization. Phishing attacks cause direct financial losses by stealing credentials and disrupting business operations. These attacks also compromise the organization’s reputation and cause long-term damage. 

API security measures can mitigate the risk of phishing by encrypting all communications, making it harder for criminals to steal credentials and authorization details. 

Regulatory compliance 

The increasing prevalence of data protection regulations like GDPR and CCPA is another use case for API email security. Failing to comply with regulations carries hefty fines and penalties. Under GDPR, an organization can be fined up to 4% of global revenue for a personal data breach following a phishing attack. API email security ensures the secure transmission of sensitive data via encryption and access controls. API security measures also enable organizations to provide an audit trail for compliance. 

Benefits of email API security

API email security offers many benefits for organizations beyond ensuring secure communications. Here are the top 4: 

  1. Enhanced sender email reputation and deliverability

API security measures like authentication protocols can improve email deliverability by establishing trust with email service providers. Authenticating emails with protocols like DKIM, SPF, DMARC, and others minimizes the chances of emails being marked as spam and prevents phishing attacks and other security risks. These protocols verify that the email comes from the domain they say they are from. The most common protocols are:

  • DomainKeys Identified Mail (DKIM): DKIM is a digital signature that uses cryptography to verify if the email came from the right domain. The DKIM record stores the domain’s public key, which the mail server checks. 
  • Sender Policy Framework (SPF): SPF records list all the IP addresses of all the servers authorized to send emails from the domain. It is like a directory that helps mail servers check against the SPF record if the sending server is on the approved list. 
  • Domain-based Message Authentication Reporting and Conformance (DMARC): The DMARC protocol tells a receiving email what to do with the results of checking SPF and DKIM. For instance, quarantine emails that fail the previous protocols, or to send reports about what emails pass or fail checks. 
  1. Regulatory compliance 

Regulations such as GDPR and CCPA require encryption, authentication, and authorization measures to ensure consumer data protection. By applying API email security processes, organizations can meet regulatory obligations.

  1. Reduced risk of email-based attacks

The encryption in API email security solutions makes it harder for cybercriminals to spoof emails and access email data. Encryption ensures that the content remains unreadable even if intercepted, making it useless for the criminal. 

  1. Essential practices for a successful implementation of API email security

Robust authentication mechanisms, being thorough with encryption algorithms, and enforcing logging and monitoring capabilities are critical steps to successfully implementing API email security. Here is a brief checklist of best practices: 

  • Implement strong authentication and authorization protocols
  • Implement access control processes
  • Encrypt requests and responses
  • Have data validation processes in place
  • Choose a secure email provider API

Key elements of email API security 

The security features in an email API ensure the protection and integrity of communications. The critical components of a robust email API security framework include authentication protocols, encryption methods, continuous monitoring for vulnerabilities/threats, and audit logging and monitoring capabilities. 


The API should provide end-to-end encryption at rest and in transit to ensure all customer data is encrypted, regardless of its state. This is especially critical when managing sensitive data, such as personal information. 

Authentication and authorization

Controlling access to the API means identifying all users and devices that use it. Access tokens such as JSON or OAuth are essential to ensure authorized users can access the email network. These tokens grant permission to access resources and data. The email API regularly monitors and logs email activity, providing security audits and vulnerability assessments. This authentication ensures incoming and outgoing communications are secure. 

Audit logging and monitoring 

An audit trail is essential for regulatory compliance and detecting and responding to security incidents. The API logs activities and monitors access patterns, allowing it to quickly identify suspicious or unauthorized behavior, track potential threats, and respond to security incidents. Audit logs also provide information for forensic analysis. 

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How can you deliver secure email features?

When you are looking to add email capabilities to your app, it is critical to ensure email security. API-based security provides an easy-to-implement solution. Here are three use cases where API email security is a requirement:

Integration with third-party email services 

Why do you need API email security when integrating with third-party email service providers? Most applications will integrate with third-party email service providers like Google, Apple, or Microsoft. These integrations involve exchanging sensitive data. Therefore, implementing API email security is critical to ensure data privacy and prevent unauthorized access. 

Leading mail providers implement security protocols to maintain the integrity and confidentiality of email communications. Here are some highlights: 

  • Google: Google’s OAuth is an authentication framework that ensures a secure and standardized method for authorizing access to Google APIs.
  • Apple: Apple’s MailKit ensures your app includes an extension with features that secure and customize email messages. 
  • Microsoft: Microsoft Graph security API connects and secures Microsoft services, products, and partners. 

The Nylas Email API is a single platform that connects and secures your integrations with users’ emails, calendars, and contacts across providers. With Nylas, you can ensure email security at scale with data encryption at rest and in transit; continuous vulnerability monitoring; continuous threat detection; as well as a bug bounty program and secure SDLC.

Internal email communication

API email security facilitates secure communication within an organization by ensuring secure communication channels and protecting sensitive information. API email security uses encryption protocols and authentication mechanisms to prevent unauthorized access and protect the confidentiality of sensitive data, thus preventing data breaches. 

Email automation and marketing campaigns

Automated email processes and marketing campaigns handle a large volume of sensitive customer data, including personal and financial information. A robust API email security protocol ensures the integrity and confidentiality of this customer data by encrypting it, minimizing the risk of man-in-the-middle and interception attacks. Because all access is authenticated, organizations can restrict who can access customer data. 

How does email API security work?

An application programming interface (API) helps share data between applications. Email API security, as the name implies, uses an email server’s API to inspect the messages before they enter the inbox or exit the outbox. API email security sits near the email service, scanning incoming and outgoing messages for threats.  

How Nylas ensures email API security

Developers must protect email communications from phishing attacks, unauthorized access, and data breaches.

The Nylas Email API provides several components that deliver enterprise-grade security. Access to sensitive data is controlled by access controls implemented based on the principle of least privilege and thorough background checks to ensure that only authorized people can access sensitive data. Nylas has comprehensive encryption capabilities both at rest and in transit. Among the critical features of Nylas Email API are robust threat prevention capabilities, such as DDoS prevention, backups, and other provisions for business continuity. 

Learn more about how Nylas Email API enhances secure communications by requesting a demo

Having Nylas in our corner took the Google OAuth Review process and empowered us to achieve verification under budget and ahead of schedule.

Rob Carrington

Head of Engineering, Harbor Plan

Frequently Asked Questions

What is an email API?

An email API is a programmable interface that enables developers to access an email provider’s functionality. 

How does an API provide security?

API email security solutions use an email server’s API to inspect messages when coming or leaving an email, detecting potential threats. 

What are some standard API email security measures?

The most common email API security measures involve authenticating and authorizing all access, encryption, and monitoring. 

What are common email security threats?

Phishing, social engineering, and ransomware are the most common email security threats. 

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Additional Resources

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