Web API vs SMTP Relay: How Should You Send Your Email?

SendGrid offers two primary methods for sending emails: the Web API and SMTP Relay, each serving different needs depending on integration requirements and user preferences. The Web API, which communicates via HTTP, is generally faster and more secure due to its use of API keys that provide an additional layer of security. It is often preferred by developers creating their own products, as it streamlines the process by reducing the potential for errors during communication. On the other hand, SMTP Relay, based on the Simple Mail Transfer Protocol, involves more back-and-forth communication, making it slightly slower and more prone to potential failures, though it remains a universal standard crucial for integrating with existing applications like CRM systems or mail clients. While SMTP Relay is widely used due to its compatibility with many systems, the Web API was specifically designed by SendGrid's founders to enhance efficiency when connecting with their system.