simple_smtp - Native SMTP Email for Eiffel

Overview

simple_smtp is a native SMTP email sending library for Eiffel. No shell commands, no curl, no external dependencies beyond EiffelNet sockets. Supports TLS, authentication, HTML emails, and attachments.

Part of the simple_* ecosystem of focused, single-purpose Eiffel libraries.

Quick Start

Installation

Add to your ECF file:

<library name="simple_smtp" location="$SIMPLE_SMTP/simple_smtp.ecf"/>

Set environment variable:

set SIMPLE_SMTP=D:\path\to\simple_smtp

Also requires: simple_base64, simple_uuid

Send an Email

local
    smtp: SIMPLE_SMTP
do
    create smtp.make ("smtp.example.com", 587)
    smtp.set_credentials ("user@example.com", "password")
    smtp.set_from ("sender@example.com", "Sender Name")
    smtp.add_to ("recipient@example.com", "Recipient")
    smtp.set_subject ("Hello from Eiffel!")
    smtp.set_body ("This is a test email.")

    if smtp.send then
        print ("Email sent!")
    else
        print ("Error: " + smtp.last_error)
    end
end

HTML Email

-- HTML only
smtp.set_html_body ("<html><body><h1>Hello!</h1></body></html>")

-- Or multipart (text + HTML fallback)
smtp.set_body_with_html (
    "Plain text for old clients",
    "<html><body><h1>HTML version</h1></body></html>"
)

With Attachments

smtp.add_attachment ("report.pdf", pdf_content, "application/pdf")
smtp.add_attachment ("data.csv", csv_content, "text/csv")

Features

Native SMTP

Pure Eiffel implementation using EiffelNet sockets. No shelling to curl or external tools.

TLS Support

STARTTLS (port 587), implicit TLS (port 465), or plain SMTP (port 25).

Authentication

AUTH LOGIN and AUTH PLAIN mechanisms with Base64 credential encoding.

Rich Content

Plain text, HTML, or multipart/alternative for email clients that prefer either.

Attachments

Add file attachments with proper MIME types and Base64 encoding.

Design by Contract

Full preconditions, postconditions, and class invariants for correctness verification.

RFC 5322 Headers

Auto-generated Date and Message-ID headers. UUID-based MIME boundaries for uniqueness.

Email Validation

Validate email addresses before sending with is_valid_email.

API Summary

Configuration

Feature	Description
`make (host, port)`	Create SMTP client for host:port
`set_credentials (user, pass)`	Set authentication credentials
`set_timeout (seconds)`	Set connection timeout
`enable_tls`	Use TLS/SSL from start (port 465)
`enable_starttls`	Upgrade to TLS via STARTTLS (port 587)

Sender & Recipients

Feature	Description
`set_from (email, name)`	Set sender (name is optional)
`add_to (email, name)`	Add To recipient
`add_cc (email, name)`	Add Cc recipient
`add_bcc (email, name)`	Add Bcc recipient (not in headers)
`clear_recipients`	Clear all recipients
`set_reply_to (email, name)`	Set Reply-To address (name optional)
`is_valid_email (address)`	Validate email format

Content

Feature	Description
`set_subject (text)`	Set email subject
`set_body (text)`	Set plain text body
`set_html_body (html)`	Set HTML body
`set_body_with_html (text, html)`	Set multipart (text + HTML)
`add_attachment (name, content, mime)`	Add file attachment
`clear_attachments`	Remove all attachments

Sending & Status

Feature	Description
`send: BOOLEAN`	Send email, returns True on success
`has_error: BOOLEAN`	Did last operation fail?
`last_error: STRING`	Error message from last failure
`last_response: STRING`	Last SMTP server response

View complete API reference →

Testing

The library includes a comprehensive test suite with 57 tests covering:

Initialization with different port configurations
Setting credentials, sender, recipients
Content handling (plain text, HTML, multipart)
Attachment management
Message building with proper MIME structure
RFC 5322 headers (Date, Message-ID)
Reply-To header support
Email address validation
UUID-based MIME boundary generation

-- Run tests
ec.exe -batch -config simple_smtp.ecf -target simple_smtp_tests -tests