diff --git a/docker/README.md b/docker/README.md
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--- a/docker/README.md
+++ b/docker/README.md
@@ -1,6 +1,7 @@
 # Docker
 
 - [commands](./commands.md)
+- [mailserver](./mailserver.md)
 - [nginx](./nginx.md)
 - [ngrok](./ngrok.md)
 - [sonarqube](./sonarqube.md)
diff --git a/docker/mailserver.md b/docker/mailserver.md
new file mode 100644
index 0000000..2b76dd0
--- /dev/null
+++ b/docker/mailserver.md
@@ -0,0 +1,79 @@
+# Mailserver
+
+- [reference](https://i12bretro.github.io/tutorials/0779.html)
+
+# Prerequisite
+
+- Domain name and static IP (EC2)
+- Docker compose
+- [Host Port Forwarding](https://docker-mailserver.github.io/docker-mailserver/latest/config/security/understanding-the-ports/#overview-of-email-ports)
+
+# Quick Setup
+
+- Set `DOMAIN_NAME` to system env by command:
+
+```bash
+DOCKER_MAILSERVER_DOMAIN_NAME=ec2-111-111-111-11.ap.aws.com
+```
+
+- Create main working directories
+
+```bash
+mkdir ~/docker/mailserver/{data,state,logs,config} -p
+```
+
+- Run `docker-compose up -d` with `docker-compose.yml`
+
+```yaml
+docker run -d --name=mailserver --hostname="$HOSTNAME" --domainname="$DOCKER_MAILSERVER_DOMAIN_NAME" -p 25:25 -p 143:143 -p 587:587 -p 993:993 -e ENABLE_SPAMASSASSIN=1 -e SPAMASSASSIN_SPAM_TO_INBOX=1 -e ENABLE_CLAMAV=1 -e ENABLE_POSTGREY=1 -e ENABLE_FAIL2BAN=0 -e ENABLE_SASLAUTHD=0 -e ONE_DIR=1 -e TZ=America/New_York -v ~/docker/mailserver/data/:/var/mail/ -v ~/docker/mailserver/state/:/var/mail-state/ -v ~/docker/mailserver/logs/:/var/log/mail/ -v ~/docker/mailserver/config/:/tmp/docker-mailserver/ --restart=unless-stopped mailserver/docker-mailserver
+```
+
+- Add admin user
+
+```bash
+docker run --rm -e MAIL_USER=admin@$DOCKER_MAILSERVER_DOMAIN_NAME -e MAIL_PASS=admin -it mailserver/docker-mailserver /bin/sh -c 'echo "$MAIL_USER|$(doveadm pw -s SHA512-CRYPT -u $MAIL_USER -p $MAIL_PASS)"' >> ~/docker/mailserver/config/postfix-accounts.cf
+```
+
+> Check that the user has been added to the configuration file `~/docker/mailserver/config/postfix-accounts.cf`
+
+# Test
+
+```javascript
+const nodemailer = require("nodemailer");
+
+let transporter = nodemailer.createTransport({
+  host: "ec2-122-248-230-39.ap-southeast-1.compute.amazonaws.com",
+  port: 587,
+  secure: false, // true for 465, false for other ports
+  auth: {
+    user: "admin@ec2-122-248-230-39.ap-southeast-1.compute.amazonaws.com",
+    pass: "admin",
+  },
+  tls: { rejectUnauthorized: false },
+  debug: true,
+  logger: true, // Enable logger
+});
+
+let mailOptions = {
+  from: "admin@ec2-122-248-230-39.ap-southeast-1.compute.amazonaws.com",
+  to: "admin@ec2-122-248-230-39.ap-southeast-1.compute.amazonaws.com",
+  subject: "Hello ✔",
+  text: "Hello world?",
+  html: "<b>Hello world?</b>",
+};
+
+transporter.verify((error) => {
+  if (error) {
+    return console.error("verify:", error);
+  }
+
+  transporter.sendMail(mailOptions, (error, info) => {
+    if (error) {
+      return console.error(error);
+    }
+    console.log("Message sent: %s", info.messageId);
+  });
+});
+```
+
+> Check that received mail is stored in `~/docker/mailserver/data/-/${user}/new`
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