<pre>
**The personal_info part contains the following ASCII characters.
1.Uppercase (A-Z) and lowercase (a-z) English letters.
2.Digits (0-9).
3.Characters ! # $ % & ' * + - / = ? ^ _ ` { | } ~
4.Character . ( period, dot or fullstop) provided that it is not the first or last character and it will not come one after the other.**
</pre>
*Example of valid email id*
<pre>
yoursite@ourearth.com
my.ownsite@ourearth.org
mysite@you.me.net
xxxx@gmail.com
xxxxxx@yahoo.com
</pre>
<pre>
xxxx.ourearth.com [@ is not present] 
xxxx@.com.my [ tld (Top Level domain) can not start with dot "." ]
@you.me.net [ No character before @ ]
xxxx123@gmail.b [ ".b" is not a valid tld ]
xxxx@.org.org [ tld can not start with dot "." ]
.xxxx@mysite.org [ an email should not be start with "." ]
xxxxx()*@gmail.com [ here the regular expression only allows character, digit, underscore and dash ]
xxxx..1234@yahoo.com [double dots are not allowed
</pre>
**javascript mail code**

    function ValidateEmail(inputText)
    {
    var mailformat = /^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/;
    if(inputText.value.match(mailformat))
    {
    document.form1.text1.focus();
    return true;
    }
    else
    {
    alert("You have entered an invalid email address!");
    document.form1.text1.focus();
    return false;
    }
    }

If you are using AngularJS, just add type="email" to the input element:

https://docs.angularjs.org/api/ng/input/input%5Bemail%5D

In case there is no input element, it can be created dynamically:

var isEmail = $compile('<input ng-model="m" type="email">')($rootScope.$new()).
    controller('ngModel').$validators["email"];

if (isEmail('email@gmail.com')) {
  console.log('valid');
} 

Following Regex validations:

• No spacial characters before @
• (-) and (.) should not be together after @
• No special characters after @ 2 characters must before @

• Email length should be less 128 characters

  function validateEmail(email) {
      var chrbeforAt = email.substr(0, email.indexOf('@'));
      if (!($.trim(email).length > 127)) {
          if (chrbeforAt.length >= 2) {
              var re = /^(([^<>()[\]{}'^?\\.,!|//#%*-+=&;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?/;
              return re.test(email);
          } else {
              return false;
          }
      } else {
          return false;
      }
  }
  

If you want to use Jquery and want to have modern approach then use JQuery input mask with validation.

http://bseth99.github.io/projects/jquery-ui/5-jquery-masks.html

Demo on how simple jquery input mask is here: http://codepen.io/anon/pen/gpRyBp

Example of simple input mask for date forexample NOT full validation

 <input id="date" type="text" placeholder="YYYY-MM-DD"/>

and the script:

 $("#date").mask("9999-99-99",{placeholder:"YYYY-MM-DD"});

In nodeJS you can also use validator node module and simply use like that

Install the library with npm install validator

var validator = require('validator');

validator.isEmail('foo@bar.com'); //=> true 

There are some complex RegEx written here, that also works.

I tested this one and it works too:

[a-zA-Z0-9._]+[@]+[a-zA-Z0-9]+[.]+[a-zA-Z]{2,6}

Please test this here : http://www.regextester.com/?fam=97334

Hope this helps.

How about creating a function which will test any string against emails’ pattern using regular expression in JavaScript, as we know email addresses can be quite different in different regions, like in UK and Australia it usually ends up with .co.uk or .com.au, so I tried to cover those as well, also check if the string passed to the function, something like this:

var isEmail = function(str) {
  return typeof str==='string' && /^[\w+\d+._]+\@[\w+\d+_+]+\.[\w+\d+._]{2,8}$/.test(str);
}

and check if it’s email like below:

isEmail('alex@example.com'); //true
isEmail('alireza@test.co.uk'); //true
isEmail('peter.example@yahoo.com.au'); //true
isEmail('alex@example.com'); //true
isEmail('peter_123@news.com'); //true
isEmail('hello7___@ca.com.pt'); //true
isEmail('example@example.co'); //true
isEmail('hallo@example.coassjj#sswzazaaaa'); //false
isEmail('hallo2ww22@example....caaaao'); //false