diff --git a/lib/smtp-connection.js b/lib/smtp-connection.js
index 280c952..3c08170 100644
--- a/lib/smtp-connection.js
+++ b/lib/smtp-connection.js
@@ -8,7 +8,7 @@ const ipv6normalize = require('ipv6-normalize');
 const sasl = require('./sasl');
 const crypto = require('crypto');
 const os = require('os');
-const punycode = require('punycode');
+const punycode = require('punycode/');
 const EventEmitter = require('events');
 const base32 = require('base32.js');
 
@@ -496,7 +496,13 @@ class SMTPConnection extends EventEmitter {
         }
 
         // block users that try to fiddle around without logging in
-        if (!this.session.user && this._isSupported('AUTH') && !this._server.options.authOptional && commandName !== 'AUTH' && this._maxAllowedUnauthenticatedCommands !== false) {
+        if (
+            !this.session.user &&
+            this._isSupported('AUTH') &&
+            !this._server.options.authOptional &&
+            commandName !== 'AUTH' &&
+            this._maxAllowedUnauthenticatedCommands !== false
+        ) {
             this._unauthenticatedCommands++;
             if (this._unauthenticatedCommands >= this._maxAllowedUnauthenticatedCommands) {
                 return this.send(421, 'Error: too many unauthenticated commands');
diff --git a/lib/smtp-server.js b/lib/smtp-server.js
index 4c91e24..8604698 100644
--- a/lib/smtp-server.js
+++ b/lib/smtp-server.js
@@ -6,7 +6,7 @@ const SMTPConnection = require('./smtp-connection').SMTPConnection;
 const tlsOptions = require('./tls-options');
 const EventEmitter = require('events');
 const shared = require('nodemailer/lib/shared');
-const punycode = require('punycode');
+const punycode = require('punycode/');
 const crypto = require('crypto');
 const base32 = require('base32.js');
 
diff --git a/package-lock.json b/package-lock.json
index e623484..38fda41 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -11,7 +11,8 @@
             "dependencies": {
                 "base32.js": "0.1.0",
                 "ipv6-normalize": "1.0.1",
-                "nodemailer": "6.9.9"
+                "nodemailer": "6.9.9",
+                "punycode": "^2.3.1"
             },
             "devDependencies": {
                 "chai": "4.4.1",
@@ -2309,7 +2310,6 @@
             "version": "2.3.1",
             "resolved": "https://registry.npmjs.org/punycode/-/punycode-2.3.1.tgz",
             "integrity": "sha512-vYt7UD1U9Wg6138shLtLOvdAu+8DsC/ilFtEVHcH+wydcSpNE20AfSOduf6MkRFahL5FY7X1oU7nKVZFtfq8Fg==",
-            "dev": true,
             "engines": {
                 "node": ">=6"
             }
diff --git a/package.json b/package.json
index 5109293..f335956 100644
--- a/package.json
+++ b/package.json
@@ -12,7 +12,8 @@
     "dependencies": {
         "base32.js": "0.1.0",
         "ipv6-normalize": "1.0.1",
-        "nodemailer": "6.9.9"
+        "nodemailer": "6.9.9",
+        "punycode": "2.3.1"
     },
     "devDependencies": {
         "chai": "4.4.1",