ESP8266 - Door Open Email Notification

This guide will show you how to set up an ESP8266 to send emails when a door opens. We will cover the setup process, the necessary parts, and provide step-by-step instructions on how to connect an ESP8266 to a door sensor and an email service. This will enhance your home's security by immediately notifying you via email whenever the door is opened.

ESP8266 NodeMCU Door Open Email Notification

Hardware Preparation

1×ESP8266 NodeMCU
1×Micro USB Cable
1×Door Sensor
1×(Optional) DC Power Jack
1×Jumper Wires
1×(Optional) ESP8266 Screw Terminal Adapter

Or you can buy the following sensor kits:

1×DIYables Sensor Kit (30 sensors/displays)
1×DIYables Sensor Kit (18 sensors/displays)
Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you. We appreciate your support.

Overview of Door Sensor and Gmail

We provide detailed guides on Door Sensors and Gmail. Every guide has full details and easy, step-by-step instructions on setting up the hardware, understanding how it works, and how to connect and program the ESP8266. You can learn more about these guides by following these links:

Wiring Diagram between Door Sensor and ESP8266

The wiring diagram between ESP8266 NodeMCU and Door Sensor

This image is created using Fritzing. Click to enlarge image

See more in ESP8266's pinout and how to supply power to the ESP8266 and other components.

ESP8266 Code

/* * This ESP8266 NodeMCU code was developed by * * This ESP8266 NodeMCU code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * */ #include <ESP8266WiFi.h> #include <ESP_Mail_Client.h> #define WIFI_SSID "YOUR_WIFI_SSID" // CHANGE IT #define WIFI_PASSWORD "YOUR_WIFI_PASSWORD" // CHANGE IT // the sender email credentials #define SENDER_EMAIL "" // CHANGE IT #define SENDER_PASSWORD "xxxx xxxx xxxx xxxx" // CHANGE IT to your Google App password #define RECIPIENT_EMAIL "" // CHANGE IT #define SMTP_HOST "" #define SMTP_PORT 587 #define DOOR_SENSOR_PIN D7 // ESP8266 pin D7 connected to door sensor's pin int door_state; // current state of door sensor int prev_door_state; // previous state of door sensor SMTPSession smtp; void setup() { Serial.begin(9600); WiFi.begin(WIFI_SSID, WIFI_PASSWORD); Serial.print("Connecting to Wi-Fi"); while (WiFi.status() != WL_CONNECTED) { Serial.print("."); delay(300); } Serial.println(); Serial.print("Connected with IP: "); Serial.println(WiFi.localIP()); Serial.println(); pinMode(DOOR_SENSOR_PIN, INPUT_PULLUP); // set ESP8266 pin to input pull-up mode door_state = digitalRead(DOOR_SENSOR_PIN); // read state } void loop() { prev_door_state = door_state; // save the last state door_state = digitalRead(DOOR_SENSOR_PIN); // read new state if (prev_door_state == LOW && door_state == HIGH) { // state change: LOW -> HIGH Serial.println("The door is opened"); String subject = "Email Notification from ESP8266"; String textMsg = "This is an email sent from ESP8266.\n"; textMsg += "Your door is opened"; gmail_send(subject, textMsg); } else if (prev_door_state == HIGH && door_state == LOW) { // state change: HIGH -> LOW Serial.println("The door is closed"); } } void gmail_send(String subject, String textMsg) { // set the network reconnection option MailClient.networkReconnect(true); smtp.debug(1); smtp.callback(smtpCallback); Session_Config config; // set the session config config.server.host_name = SMTP_HOST; config.server.port = SMTP_PORT; = SENDER_EMAIL; config.login.password = SENDER_PASSWORD; config.login.user_domain = F(""); config.time.ntp_server = F(","); config.time.gmt_offset = 3; config.time.day_light_offset = 0; // declare the message class SMTP_Message message; // set the message headers = F("ESP8266"); = SENDER_EMAIL; message.subject = subject; message.addRecipient(F("To Whom It May Concern"), RECIPIENT_EMAIL); message.text.content = textMsg; message.text.transfer_encoding = "base64"; message.text.charSet = F("utf-8"); message.priority = esp_mail_smtp_priority::esp_mail_smtp_priority_low; // set the custom message header message.addHeader(F("Message-ID: <>")); // connect to the server if (!smtp.connect(&config)) { Serial.printf("Connection error, Status Code: %d, Error Code: %d, Reason: %s\n", smtp.statusCode(), smtp.errorCode(), smtp.errorReason().c_str()); return; } if (!smtp.isLoggedIn()) { Serial.println("Not yet logged in."); } else { if (smtp.isAuthenticated()) Serial.println("Successfully logged in."); else Serial.println("Connected with no Auth."); } // start sending Email and close the session if (!MailClient.sendMail(&smtp, &message)) Serial.printf("Error, Status Code: %d, Error Code: %d, Reason: %s\n", smtp.statusCode(), smtp.errorCode(), smtp.errorReason().c_str()); } // callback function to get the Email sending status void smtpCallback(SMTP_Status status) { // print the current status Serial.println(; // print the sending result if (status.success()) { Serial.println("----------------"); Serial.printf("Email sent success: %d\n", status.completedCount()); Serial.printf("Email sent failed: %d\n", status.failedCount()); Serial.println("----------------\n"); for (size_t i = 0; i < smtp.sendingResult.size(); i++) { // get the result item SMTP_Result result = smtp.sendingResult.getItem(i); Serial.printf("Message No: %d\n", i + 1); Serial.printf("Status: %s\n", result.completed ? "success" : "failed"); Serial.printf("Date/Time: %s\n", MailClient.Time.getDateTimeString(result.timestamp, "%B %d, %Y %H:%M:%S").c_str()); Serial.printf("Recipient: %s\n", result.recipients.c_str()); Serial.printf("Subject: %s\n", result.subject.c_str()); } Serial.println("----------------\n"); // free the memory smtp.sendingResult.clear(); } }

Detailed Instructions

To get started with ESP8266 on Arduino IDE, follow these steps:

  • Check out the how to setup environment for ESP8266 on Arduino IDE tutorial if this is your first time using ESP8266.
  • Wire the components as shown in the diagram.
  • Mount the door sensor on your door.
  • Connect the ESP8266 board to your computer using a USB cable.
  • Open Arduino IDE on your computer.
  • Choose the correct ESP8266 board, such as (e.g. NodeMCU 1.0 (ESP-12E Module)), and its respective COM port.
  • In the Arduino IDE, click on the Library Manager icon in the left menu to open it.
  • Search for ESP Mail Client and find ESP Mail Client by Mobizt.
  • Click Install button to add the ESP Mail Client library.
ESP8266 NodeMCU ESP Mail Client library
  • Copy the code and open it with Arduino IDE.
  • Enter your WiFi information (network name and password) in the code. Update WIFI_SSID and WIFI_PASSWORD with your details.
  • Change the email and password of the sender in the code. Change SENDER_EMAIL and SENDER_PASSWORD to your email and password.
  • Update the receiver's email address in RECIPIENT_EMAIL to your own email, if needed. It can be the same as the sender's email.


Ensure the sender's email uses Gmail. Use the App password created earlier as the sender's password. The recipient's email can be of any type.

  • Click the Upload button in the Arduino IDE to send the code to the ESP8266.
  • Open the Serial Monitor.
  • Open the door.
  • Check the results on the Serial Monitor.
The door is opened #### Email sent successfully > C: Email sent successfully ---------------- Message sent success: 1 Message sent failed: 0 ---------------- Message No: 1 Status: success Date/Time: May 27, 2024 04:42:50 Recipient: Subject: Email Notification from ESP8266 ----------------
Autoscroll Show timestamp
Clear output
9600 baud  
  • Check the email inbox of the person you sent the email to. You should find an email that looks like this:
ESP8266 NodeMCU door sensor email

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