ESP8266 - Gmail

This guide will show you how to set up an ESP8266 to send an email through your Gmail account. The email will be sent from a Gmail account and can be received by any email account.

ESP8266 NodeMCU Gmail

Hardware Preparation

1×ESP8266 NodeMCU
1×Micro USB Cable
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.


To use the code, you need a Gmail account and a special app password. Here are the key details to remember:

  1. Create a new Gmail account specifically for testing instead of using your regular one, to avoid any issues.
  2. The password used in the ESP8266 code is not the same as your Gmail account password. You need to obtain an "App Password" from your Google Account by following certain instructions.

Here are the steps, one by one:

Gmail security
  • Activate 2-Step Verification (This is essential before you can use app passwords).
  • Visit the Google App Passwords website and create an app password. You can name it whatever you like.
Google App Passwords
  • Click the Create button and a 16-digit password will be displayed for you.
Gmail App Passwords
  • Save this 16-digit number. You will need it for the ESP8266 code in the next step.


Google's user interface may change. If you do not see "App Passwords" after following the steps above, search for "How to get Google App Passwords" to find updated instructions.

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 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(); String subject = "Email Notification from ESP8266"; String textMsg = "This is an email sent from ESP8266.\n"; textMsg += "Sensor value: "; textMsg += "15"; // OR replace this value read from a sensor gmail_send(subject, textMsg); } void loop() { // YOUR OTHER CODE HERE } 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("Message sent success: %d\n", status.completedCount()); Serial.printf("Message 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.
  • 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.
  • Click on the Library Manager icon on the left in the Arduino IDE.
  • Search for ESP Mail Client and choose the one by Mobizt.
  • Press the Install button to add the ESP Mail Client library.
ESP8266 NodeMCU ESP Mail Client library
  • Copy the above code and open it using the Arduino IDE.
  • Update your WiFi information by changing WIFI_SSID and WIFI_PASSWORD to your WiFi network's SSID and password.
  • Enter your email and password in the code under SENDER_EMAIL and SENDER_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.


  • The sender's email should be a Gmail account.
  • The sender's password is the App password given in the previous step.
  • The recipient's email can be any kind.
  • Click on the Upload button in Arduino IDE to send the code to ESP8266.
  • Open the Serial Monitor.
  • Check the results on the Serial Monitor.
#### Message sent successfully > C: message 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  
  • Look in the email inbox of the person you sent the email to. You will find an email similar to this:
ESP8266 NodeMCU sends email

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