diff --git a/conf/wide.go b/conf/wide.go
index a789795..b1e7780 100644
--- a/conf/wide.go
+++ b/conf/wide.go
@@ -57,6 +57,7 @@ type LatestSessionContent struct {
 type User struct {
 	Name                 string
 	Password             string
+	Email                string
 	Workspace            string // the GOPATH of this user
 	Locale               string
 	GoFormat             string
@@ -67,9 +68,9 @@ type User struct {
 	LatestSessionContent *LatestSessionContent
 }
 
-// NewUser creates a user with the specified username, password and workspace.
-func NewUser(username, password, workspace string) *User {
-	return &User{Name: username, Password: password, Workspace: workspace,
+// NewUser creates a user with the specified username, password, email and workspace.
+func NewUser(username, password, email, workspace string) *User {
+	return &User{Name: username, Password: password, Email: email, Workspace: workspace,
 		Locale: Wide.Locale, GoFormat: "gofmt", FontFamily: "Helvetica", FontSize: "13px", Theme: "default",
 		Editor: &Editor{FontFamily: "Consolas, 'Courier New', monospace", FontSize: "inherit", Theme: "wide",
 			TabSize: "4"}}
diff --git a/conf/wide.json b/conf/wide.json
index 25c4b49..71c259e 100644
--- a/conf/wide.json
+++ b/conf/wide.json
@@ -17,6 +17,7 @@
         {
             "Name": "admin",
             "Password": "admin",
+            "Email": "",
             "Workspace": "${GOPATH}",
             "Locale": "en_US",
             "GoFormat": "gofmt",
diff --git a/i18n/en_US.json b/i18n/en_US.json
index 339aaa0..2a69661 100644
--- a/i18n/en_US.json
+++ b/i18n/en_US.json
@@ -118,6 +118,7 @@
     "team": "Team",
     "sing_up_error": "Sign Up Error",
     "user_name_ruler": "Username only by az, AZ, 0-9, _ consisting of a length of 16",
+    "invalid_email": "Invalid Email",
     "password_no_match": "Password doesn't match the confirmation",
     "discard": "Discard",
     "close": "Close",
@@ -154,5 +155,6 @@
     "select_identifier": "Select Identifier",
     "source": "Source",
     "toggle_comment": "Toggle Comment",
-    "find_in_files": "Find in Files"
+    "find_in_files": "Find in Files",
+    "email": "Email"
 }
\ No newline at end of file
diff --git a/i18n/ja_JP.json b/i18n/ja_JP.json
index e2e0db0..d3c11d8 100644
--- a/i18n/ja_JP.json
+++ b/i18n/ja_JP.json
@@ -118,6 +118,7 @@
     "team": "チーム",
     "sing_up_error": "登録に失敗しました",
     "user_name_ruler": "16の長さからなる_ AZ、AZ、0-9、によってユーザ名のみ",
+    "invalid_email": "無効な電子メール",
     "password_no_match": "一貫性のないパスワード入力",
     "discard": "あきらめる",
     "close": "クローズ",
@@ -154,5 +155,6 @@
     "select_identifier": "選択識別子",
     "source": "ソース",
     "toggle_comment": "トグルコメント",
-    "find_in_files": "ファイルから検索"
+    "find_in_files": "ファイルから検索",
+    "email": "Eメール"
 }
diff --git a/i18n/zh_CN.json b/i18n/zh_CN.json
index 394fd2f..072947c 100644
--- a/i18n/zh_CN.json
+++ b/i18n/zh_CN.json
@@ -118,6 +118,7 @@
     "team": "团队",
     "sing_up_error": "注册失败",
     "user_name_ruler": "用户名只能由 a-z, A-Z, 0-9, _ 组成，长度为16",
+    "invalid_email": "无效的电子邮件",
     "password_no_match": "密码输入不一致",
     "discard": "放弃",
     "close": "关闭",
@@ -154,5 +155,6 @@
     "select_identifier": "选择标识符",
     "source": "源码",
     "toggle_comment": "注释",
-    "find_in_files": "在文件中查找"
+    "find_in_files": "在文件中查找",
+    "email": "电子邮件"
 }
\ No newline at end of file
diff --git a/i18n/zh_TW.json b/i18n/zh_TW.json
index 22bbbdc..31a7d70 100644
--- a/i18n/zh_TW.json
+++ b/i18n/zh_TW.json
@@ -118,6 +118,7 @@
     "team": "團隊",
     "sing_up_error": "註冊失敗",
     "user_name_ruler": "用戶名只能由az, AZ, 0-9, _ 組成，長度為16",
+    "invalid_email": "無效的電子郵件",
     "password_no_match": "密碼輸入不一致",
     "discard": "放棄",
     "close": "關閉",
@@ -154,5 +155,6 @@
     "select_identifier": "選擇標識符",
     "source": "源代碼",
     "toggle_comment": "註釋",
-    "find_in_files": "在文件中查找"
+    "find_in_files": "在文件中查找",
+    "email": "電子郵件"
 }
\ No newline at end of file
diff --git a/session/users.go b/session/users.go
index a6b3dad..d2fd5a6 100644
--- a/session/users.go
+++ b/session/users.go
@@ -32,7 +32,10 @@ import (
 )
 
 const (
+	// TODO: i18n
+
 	userExists      = "user exists"
+	emailExists     = "email exists"
 	userCreated     = "user created"
 	userCreateError = "user create error"
 )
@@ -89,6 +92,7 @@ func PreferenceHandler(w http.ResponseWriter, r *http.Request) {
 		Workspace        string
 		Username         string
 		Password         string
+		Email            string
 		Locale           string
 		Theme            string
 		EditorFontFamily string
@@ -110,6 +114,7 @@ func PreferenceHandler(w http.ResponseWriter, r *http.Request) {
 	user.GoFormat = args.GoFmt
 	user.Workspace = args.Workspace
 	user.Password = args.Password
+	user.Email = args.Email
 	user.Locale = args.Locale
 	user.Theme = args.Theme
 	user.Editor.FontFamily = args.EditorFontFamily
@@ -240,21 +245,22 @@ func SignUpUser(w http.ResponseWriter, r *http.Request) {
 
 	username := args["username"].(string)
 	password := args["password"].(string)
+	email := args["email"].(string)
 
-	msg := addUser(username, password)
+	msg := addUser(username, password, email)
 	if userCreated != msg {
 		succ = false
 		data["msg"] = msg
 	}
 }
 
-// addUser add a user with the specified username and password.
+// addUser add a user with the specified username, password and email.
 //
 //  1. create the user's workspace
 //  2. generate 'Hello, 世界' demo code in the workspace
 //  3. update the user customized configurations, such as style.css
 //  4. serve files of the user's workspace via HTTP
-func addUser(username, password string) string {
+func addUser(username, password, email string) string {
 	addUserMutex.Lock()
 	defer addUserMutex.Unlock()
 
@@ -262,13 +268,17 @@ func addUser(username, password string) string {
 		if user.Name == username {
 			return userExists
 		}
+
+		if user.Email == email {
+			return emailExists
+		}
 	}
 
 	firstUserWorkspace := conf.Wide.GetUserWorkspace(conf.Wide.Users[0].Name)
 	dir := filepath.Dir(firstUserWorkspace)
 	workspace := filepath.Join(dir, username)
 
-	newUser := conf.NewUser(username, password, workspace)
+	newUser := conf.NewUser(username, password, email, workspace)
 	conf.Wide.Users = append(conf.Wide.Users, newUser)
 
 	if !conf.Save() {
diff --git a/static/css/sign.css b/static/css/sign.css
index fb8eee8..35a9d9b 100644
--- a/static/css/sign.css
+++ b/static/css/sign.css
@@ -155,7 +155,7 @@
 }
 
 .form.sign-up {
-    margin-top: -71px;
+    margin-top: -108px;
 }
 
 #signUpBtn {
diff --git a/static/js/menu.js b/static/js/menu.js
index dc90b9b..b2df2d7 100644
--- a/static/js/menu.js
+++ b/static/js/menu.js
@@ -364,6 +364,7 @@ var menu = {
                             $goFmt = $dialogPreference.find("input[name=goFmt]"),
                             $workspace = $dialogPreference.find("input[name=workspace]"),
                             $password = $dialogPreference.find("input[name=password]"),
+                            $email = $dialogPreference.find("input[name=email]"),
                             $locale = $dialogPreference.find("input[name=locale]"),
                             $theme = $dialogPreference.find("input[name=theme]"),
                             $editorFontFamily = $dialogPreference.find("input[name=editorFontFamily]"),
@@ -378,6 +379,7 @@ var menu = {
                         "goFmt": $goFmt.val(),
                         "workspace": $workspace.val(),
                         "password": $password.val(),
+                        "email": $email.val(),
                         "locale": $locale.val(),
                         "theme": $theme.val(),
                         "editorFontFamily": $editorFontFamily.val(),
@@ -401,6 +403,7 @@ var menu = {
                             $goFmt.data("value", $goFmt.val());
                             $workspace.data("value", $workspace.val());
                             $password.data("value", $password.val());
+                            $email.data("value", $email.val());
                             $locale.data("value", $locale.val());
                             $theme.data("value", $theme.val());
                             $editorFontFamily.data("value", $editorFontFamily.val());
diff --git a/views/preference.html b/views/preference.html
index 94eee8b..29c5127 100644
--- a/views/preference.html
+++ b/views/preference.html
@@ -88,6 +88,10 @@
                 </select>
                 <br/>
             </label>
+            <label>
+                {{.i18n.email}}{{.i18n.colon}}
+                <input data-value="{{.user.Email}}" value="{{.user.Email}}" name="email"/>
+            </label>
             <input data-value="{{.user.Locale}}" value="{{.user.Locale}}" name="locale" hidden="hidden" />
             <label>
                 {{.i18n.workspace}}{{.i18n.colon}}
diff --git a/views/sign_up.html b/views/sign_up.html
index c717a65..ce072ce 100644
--- a/views/sign_up.html
+++ b/views/sign_up.html
@@ -34,6 +34,7 @@
                         <div id="dir" data-dir="{{.dir}}{{.pathSeparator}}">{{.dir}}{{.pathSeparator}}</div>
                     </div>
                     <input id="username" placeholder="Username"/><br/>
+                    <input id="email" placeholder="Email"/><br/>
                     <input id="password" type="password" placeholder="Password"/><br/>
                     <input id="confirmPassword" type="password" placeholder="Confirm your password"/>
                     <button id="signUpBtn" class="button">{{.i18n.sign_up}}</button>
@@ -60,6 +61,10 @@
             $("#msg").text("{{.i18n.user_name_ruler}}").show();
             $("#username").focus();
             return false;
+        } else if (!/^((([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+(\.([a-z]|\d|[!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+)*)|((\x22)((((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(([\x01-\x08\x0b\x0c\x0e-\x1f\x7f]|\x21|[\x23-\x5b]|[\x5d-\x7e]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(\\([\x01-\x09\x0b\x0c\x0d-\x7f]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]))))*(((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(\x22)))@((([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.)+(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])))\.?$/i.test($("#email").val())) {
+            $("#msg").text("{{.i18n.invalid_email}}").show();
+            $("#email").focus();
+            return false;
         } else if ($.trim($("#password").val()) === "") {
             $("#msg").text("{{.i18n.sing_up_error}}").show();
             $("#password").focus();
@@ -72,7 +77,8 @@
 
         var request = {
             username: $("#username").val(),
-            password: $("#password").val()
+            password: $("#password").val(),
+            email: $("#email").val()
         };
         $.ajax({
             type: 'POST',
@@ -97,7 +103,7 @@
                     || $.trim($(this).val()).length > 16) {
                 $("#msg").text("{{.i18n.user_name_ruler}}").show();
             } else {
-                $("#password").focus();
+                $("#email").focus();
                 $("#msg").hide();
             }
         } else {
@@ -112,6 +118,18 @@
         }
     }).focus();
 
+    $("#email").keydown(function (event) {
+        if (event.which === 13) {
+            if ($.trim($(this).val()) === "") {
+                $("#msg").text("{{.i18n.invalid_email}}").show();
+            } else {
+                $("#password").focus();
+            }
+        } else {
+            $("#msg").hide();
+        }
+    });
+
     $("#password").keydown(function (event) {
         if (event.which === 13) {
             if ($.trim($(this).val()) === "") {