HS SMTP is a software library in C (supplied with full source code) which implements the client side of Simple Mail Transfer Protocol (SMTP) over TCP socket layer according to RFC 821. Support for transfer of basic message header and text is provided

From version 1.1, HS SMTP supports ESMTP extension for LOGIN Authentication using Base64 encoding and message sending to multiple recipients from address list.

From version 1.2 HS SMTP supports sending binary file attachments using MIME version 1.0 base64 encoding

From version 2.0.0 HS SMTP supports secure SMTP over TLS / SSL (RFC 3207)

To send a text email message to any address on the internet, the user application calls a single function HsSmtpSendMail, specifying mail server name or IP address, sender address, recipient address, message text buffer and length, subject, cc and an event callback function to use for reporting of operation result and server errors.

HS SMTP library then resolves the server name, connects to it and transmits the message according to SMTP RFC 821 protocol. HS SMTP Library incorporates the necessary state machine, transparency procedures, and server response processing required to comply to a simple and robust SMTP client implementation.

Modular design makes it easy to port HS SMTP protocol module to any environment. HS SMTP internally at a lower layer interfaces to HS Sock library which provides TCP transport services. User application need not worry about Winsock – HS SMTP does all transmission, reception and event handling over socket layer.

Features
-SMTP Client Operation
-Server name resolution
-Supports up to 5 contexts
-Message Header Transfer
-Message Text Transfer
-Asynchonous Operation
-Sending MIME base64 binary file attachments
-ESMTP Authentication
-Secure SMTP over TLS (RFC 3207)
* This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit