(function($){
    $.fn.autoMail = function(options){
        var autoMail = $(this);
        var _value   = '';
        var _index   = -1;
        var _width   = autoMail.outerWidth();
        var _height  = autoMail.outerHeight();
        var _left    = autoMail.offset().left;
        var _top     = autoMail.offset().top;
        autoMail.defaults = {
            deValue : '請輸入郵箱地址',
            textCls : 'text-gray',
            listCls : 'list-mail',
            listTop : 1,
            mailArr  : ["qq.com","gmail.com","126.com","163.com","hotmail.com","yahoo.com","yahoo.com.cn","live.com","sohu.com","sina.com"]
        }
        //初始化
        autoMail.init = function(){
            autoMail.vars = $.extend({},autoMail.defaults,options);
            autoMail.val(autoMail.vars.deValue).addClass(autoMail.vars.textCls);
            autoMail.click(function(event){
                autoMail.select().removeClass(autoMail.vars.textCls);
                if(autoMail.val() != autoMail.vars.deValue){
                    autoMail.add();
                    autoMail.order(_value);
                    autoMail.list.find('.item').each(function(){
                        if($(this).text() == autoMail.val()){
                            $(this).siblings('.item').removeClass('select');
                            $(this).addClass('select');
                            return false;
                        }
                    })
                }
                event.stopPropagation();
            })
            autoMail.blur(function(event){
                if(autoMail.val() == '' || autoMail.val() == autoMail.vars.deValue){
                    alert(autoMail.val())
                    autoMail.val(autoMail.vars.deValue).addClass(autoMail.vars.textCls);
                }
            })
            //文本域鍵盤松開事件
            autoMail.keyup(function(event){
                if($(autoMail.list).length == 0){
                    autoMail.add();
                }
                if(autoMail.list.length > 0){
                    var keyCode = event.keyCode;
                    //alert(keyCode)
                    switch(keyCode){
                        case 13:
                            autoMail.remove();
                            autoMail.blur();
                            break;
                        case 38:
                            _index--;
                            if(_index < 0){
                                _index = 0;
                            }
                            autoMail.keyOperate(_index);
                            break;
                        case 40:
                            _index++;
                            if(_index > $('.item',autoMail.list).length - 1){
                                _index = ('.item',autoMail.list).length - 1
                            }
                            autoMail.keyOperate(_index);
                            break;
                        default:
                            if(autoMail.val().indexOf('@') < 0){
                                _value = autoMail.val();
                                autoMail.order(_value);     
                            }    
                    }  
                }
            })
            $(document).click(function(){
                if($(autoMail.list).length > 0){
                    autoMail.remove();
                    autoMail.blur();
                }
            })
        }
        //創建列表
        autoMail.create = function(){
            var li = '';
            for(var i = 0; i < autoMail.vars.mailArr.length; i++){
                li += '<li class="item">'+ '<span class="style">' + '@' + autoMail.vars.mailArr[i] + '</span>' + '</li>';
            }
            autoMail.list = $('<div class="'+ autoMail.vars.listCls +'"><ul>'+ li +'</ul></div>');
            autoMail.list.css({
                'position' : 'absolute',
                'left'     : _left,
                'top'      : _top + _height + autoMail.vars.listTop,
                'min-width': _width
            })
            autoMail.list.appendTo($('body'));
            //郵箱列表綁定事件
            autoMail.list.find('.item').click(function(event){
                autoMail.getVal($(this));
                autoMail.remove();
                event.stopPropagation();
            })
            autoMail.list.find('.item').hover(
                function(){ $(this).addClass('hover'); },
                function(){ $(this).removeClass('hover'); }
            )
            return autoMail.list;
        }
        //序列化列表
        autoMail.order = function(_value){
            $('.name',autoMail.list).remove();
            var name = $('<span class="name">'+ _value +'</span>');
            $('.item',autoMail.list).prepend(name);
        }
        //添加列表
        autoMail.add = function(){
            if(typeof autoMail.list == 'undefined' || autoMail.list.length < 1) autoMail.create();
        }
        //移除列表
        autoMail.remove = function(){
            if(autoMail.list.length > 0){
                autoMail.list.remove();
                delete autoMail.list;
            }
        }
        //獲取值
        autoMail.getVal = function(obj){
            if($('.name',obj).text() != ''){
                var selectValue = obj.text();
                autoMail.val(selectValue);  
            }else{
                return false;
            }
        }
        //鍵盤操作
        autoMail.keyOperate = function(_index){
            $('.item',autoMail.list).eq(_index).addClass('hover').siblings('.item').removeClass('hover');
            autoMail.val($('.item',autoMail.list).eq(_index).text());
        }
        //開始初始話動作...
        autoMail.init();
    }
})(jQuery)

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
        <title>無標題文檔</title>
        <script type="text/javascript" src="./jquery.js"></script>
        <script type="text/javascript" src="./autoMail.js"></script>
        <script type="text/javascript">
        $(function(){
            $('.automail').autoMail();
        }) 
        </script>
        <style type="text/css">
        *{padding: 0; margin: 0;}
        body{font-family: "微軟雅黑"; color: #333; font-size: 12px;}
        ul{list-style: none;}
        input{ width: 180px; height: 16px; line-height: 16px; margin: 100px; padding: 4px; border: 1px solid #aaa; font-size: 12px; font-family: "微軟雅黑"; }
        .list-mail ul{ border: 1px solid #aaa; line-heihgt: 24px; padding: 6px; }
        .list-mail li{ cursor: pointer; padding: 2px 3px; margin-bottom: 2px; }
        .list-mail .name{ color: #982114; }
        .list-mail .hover{ background: #fefacf; }
        .list-mail .select{ background: #dedaae; }
        </style>
    </head>
    <body>
        <div class="test"></div>
        <input type="text" class="automail" />
    </body>
</html>