EMailSender Library v4.1.3

EMailSender Logo

A comprehensive Arduino library for sending emails via SMTP with full support for attachments, multiple recipients, and secure connections (SSL/TLS and STARTTLS).

Author: Renzo Mischianti
Website: www.mischianti.org
GitHub: @xreef

📚 Documentation & Tutorials

Complete tutorials and articles available on mischianti.org:

General Documentation

🌐 EMailSender Library Home - Main library page with all articles
📖 🇺🇸 Library Forum & Support - Community support and discussions
📖 🇮🇹 Forum e supporto alla libreria - Community support and discussions

Platform-Specific Guides

ESP32 & ESP8266 Tutorials

📧 How to Send Emails with Attachments on ESP32/ESP8266 (EMailSender v4.0.0 & STARTTLS) - Covers the latest v4.0.0 library update. Focuses on STARTTLS (port 587) support, which is required for modern Gmail. Includes wiring for SD cards.
📧 ESP32: Send email with attachments (Gmail, Yahoo, Outlook) - Complete guide for ESP32
🔐 ESP32: Secure email with SSL/TLS and attachments - SSL/TLS configuration
📎 ESP32: Manage SPIFFS and send attachments - SPIFFS file attachments
💾 ESP32: LittleFS filesystem and email attachments - LittleFS integration
📁 ESP32: FFAT filesystem and large file attachments - FFAT for large files
📧 ESP8266: Send email with attachments - Complete guide for ESP8266
📎 ESP8266: Manage SPIFFS and send attachments - SPIFFS integration
💾 ESP8266: LittleFS filesystem and email attachments - LittleFS support

Arduino Tutorials

📧 Arduino UNO/Mega and Ethernet: Sending Emails with Attachments (EMailSender v4.0.0 Library) - Specifically for boards with limited SRAM (UNO/Mega). Uses Ethernet shields (W5100/W5500). Addresses memory optimization techniques for v4.0.0.
📧 Arduino: Send email with attachments (Ethernet shield) - Arduino with ENC28J60
🔐 Arduino: Secure SSL/TLS email with Ethernet - SSL configuration for Arduino
📎 Arduino: SD card attachments with Ethernet - SD card integration
📡 Arduino: WiFiNINA shield and email sending - WiFiNINA shield

STM32 Tutorials

📧 STM32: Send email with W5500 Ethernet - STM32 with W5500
🔐 STM32: Secure SSL/TLS email with W5500 - SSL/TLS for STM32
📎 STM32: SPI Flash attachments with email - SPI Flash integration
🌐 STM32: Send email with ENC28J60 - ENC28J60 Ethernet

Raspberry Pi Pico (RP2040) Tutorials

📧 Raspberry Pi Pico W: Send email with attachments - Pico W WiFi
💾 Raspberry Pi Pico: LittleFS and email attachments - LittleFS integration

Advanced Topics

🔐 STARTTLS vs SSL/TLS: Understanding secure email - NEW! Security protocols explained
📮 Gmail App Passwords: Setup guide - Configure Gmail for Arduino
🛠️ Troubleshooting email sending issues - Common problems and solutions

✨ Features

Core Features

✅ Send emails via SMTP with authentication
✅ Multiple recipients (To, Cc, Bcc)
✅ HTML and plain text email formats
✅ File attachments from various storage systems
✅ Base64 encoding for attachments
✅ Custom sender name and email address
✅ Subject and message body customization

Security Features (NEW in v4.0.0)

✅ STARTTLS support (Port 587) - NEW!
✅ Implicit SSL/TLS (Port 465)
✅ Multiple authentication methods:
- AUTH LOGIN (default)
- AUTH PLAIN (SASL)
- CRAM-MD5 (ESP32 only)
✅ Internal SSLClient for STARTTLS on ESP32/ESP8266
✅ OpenSLab SSLClient (BearSSL) for Ethernet shields

Network Support

Multiple network interfaces (WiFi, Ethernet, WiFiNINA)
Automatic IP resolution
Connection retry logic
Flexible client configuration

🎯 Supported Platforms

| Platform | WiFi | Ethernet | SSL/TLS | STARTTLS | |----------|------|----------|---------|----------| | ESP32 | ✅ | ✅ | ✅ | ✅ | | ESP8266 | ✅ | ✅ | ✅ | ✅ | | Arduino Mega/Uno | ❌ | ✅ | ❌ | ❌ | | Arduino SAMD | ✅ | ✅ | ✅ | ✅ | | STM32 | ❌ | ✅ | ✅ | ✅ | | Raspberry Pi Pico (RP2040) | ✅ | ✅ | ✅ | ✅ |

⚠️ IMPORTANTE - Arduino Mega/Uno e SSL/TLS:

Arduino Mega and Uno DO NOT support SSL/TLS due to severe RAM limitations:

Arduino Mega has only 8KB of RAM

Arduino Uno has only 2KB of RAM

BearSSL for SSL/TLS requires at least 24KB of RAM for encryption buffers

Alternative solutions for Arduino Mega/Uno:

✅ Use non-secure SMTP (port 25) - Works but not recommended

✅ Use a local SMTP relay - Configure a local server that handles SSL

✅ Switch to ESP32/ESP8266 - They have more RAM and native SSL/TLS support

✅ Use Arduino SAMD (MKR WiFi 1010) - Has 32KB RAM and supports SSL/TLS

Arduino Mega/Uno examples in this library use only non-secure SMTP!

🌐 Supported Network Interfaces

WiFi (ESP32/ESP8266) - WiFiClient / WiFiClientSecure
WiFi (SAMD/MBED) - WiFiNINA library
Ethernet W5100/W5200/W5500 - Standard Ethernet library
Ethernet ENC28J60 - UIPEthernet library
Ethernet with SSL - SSLClient wrapper for secure connections

💾 Supported Storage Systems

Internal Storage (Microcontroller Flash)

SPIFFS (ESP32, ESP8266)
LittleFS (ESP32, ESP8266, RP2040)
FFAT (ESP32)
SPIFM (SPI Flash with Adafruit_SPIFlash)
Generic stream and string attachments option

External Storage (SD/microSD Cards)

SD (Standard SD library)
SdFat (Version 1.x for RP2040/ESP8266)
SdFat2 (Version 2.x for modern platforms)

📦 Installation

Arduino IDE

Open Arduino IDE
Go to Sketch > Include Library > Manage Libraries
Search for "EMailSender"
Click Install

PlatformIO

Add to your platformio.ini:

lib_deps = 
    xreef/EMailSender@^4.1.3

Manual Installation

Download the library from GitHub
Extract to Arduino libraries folder
Restart Arduino IDE

🚀 Basic Usage

Simple Email (ESP32 with Gmail)

#include <WiFi.h>
#include <EMailSender.h>

const char* ssid = "YOUR_SSID";
const char* password = "YOUR_PASSWORD";

// Gmail SMTP configuration
EMailSender emailSend("your.email@gmail.com", 
                      "your_app_password",
                      "your.email@gmail.com", 
                      "Your Name",
                      "smtp.gmail.com", 
                      587);  // Port 587 for STARTTLS

void

EMailSender

Install / Use

README