API Reference

This document describes the libESMTP v1.1 programming interface.

The latest version of this document is always available at libesmtp.github.io.

The libESMTP API is intended for use as an SMTP client within a Mail User Agent (MUA) or other program that wishes to submit mail to a preconfigured Message Submission Agent (MSA), sometimes known as a smart host.

The documentation is believed to be accurate however:

Much of it is apocryphal or, at the very least, wildly inaccurate. However, where it is inaccurate, it is definitively inaccurate.

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• Introduction
  • Overview
  • API
  • Usage
  • Opaque Pointers
  • Thread Safety
  • Signal Handling
• API Overview
• TLS Certificates
  • Server Certificate Validation
  • Client Certificate
  • Initialisation
  • OpenSSL Default Paths
  • Certificate Passwords
  • Permissions
  • Connection
  • Alternative SSL_CTX Initialisation
• libESMTP Types
• Core API
• Delivery Status Notification (DSN)
• Size Extention
• 8bit-MIME Transport Extension
• Deliver By Extension
• Callbacks
• SMTP Protocol
• Tear Down Session
• Application Data
• Miscellaneous APIs
• StartTLS Extension
• Auth Extension
  • Authentication Contexts
• Auth Client
• Message Callbacks
• Message Headers
  • List Values
  • Required Headers
  • Preserved Headers
  • Prohibited Headers
• Remote Message Queue Starting (ETRN)
• Errors
• Event Callback
• TLS Event Callback
• Licence
• Index of Symbols