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regex – How to validate an email address in JavaScript

Posted by: admin February 21, 2020 Leave a comment

Questions:

Is there a regular expression to validate an email address in JavaScript?

How to&Answers:

Using regular expressions is probably the best way. You can see a bunch of tests here (taken from chromium)

function validateEmail(email) {
    var re = /^(([^<>()\[\]\.,;:\[email protected]"]+(\.[^<>()\[\]\.,;:\[email protected]"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
    return re.test(String(email).toLowerCase());
}

Here’s the example of regular expresion that accepts unicode:

var re = /^(([^<>()\[\]\.,;:\[email protected]\"]+(\.[^<>()\[\]\.,;:\[email protected]\"]+)*)|(\".+\"))@(([^<>()[\]\.,;:\[email protected]\"]+\.)+[^<>()[\]\.,;:\[email protected]\"]{2,})$/i;

But keep in mind that one should not rely only upon JavaScript validation. JavaScript can easily be disabled. This should be validated on the server side as well.

Here’s an example of the above in action:

function validateEmail(email) {
  var re = /^(([^<>()[\]\.,;:\[email protected]\"]+(\.[^<>()[\]\.,;:\[email protected]\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
  return re.test(email);
}

function validate() {
  var $result = $("#result");
  var email = $("#email").val();
  $result.text("");

  if (validateEmail(email)) {
    $result.text(email + " is valid :)");
    $result.css("color", "green");
  } else {
    $result.text(email + " is not valid :(");
    $result.css("color", "red");
  }
  return false;
}

$("#validate").on("click", validate);
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<form>
  <p>Enter an email address:</p>
  <input id='email'>
  <button type='submit' id='validate'>Validate!</button>
</form>

<h2 id='result'></h2>

Answer:

I’ve slightly modified Jaymon’s answer for people who want really simple validation in the form of:

[email protected]

The regular expression:

/\[email protected]\S+\.\S+/

Example JavaScript function:

function validateEmail(email) 
{
    var re = /\[email protected]\S+\.\S+/;
    return re.test(email);
}

Answer:

Just for completeness, here you have another RFC 2822 compliant regex

The official standard is known as RFC 2822. It describes the syntax that valid email addresses must adhere to. You can (but you shouldn’tread on) implement it with this regular expression:

(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*|"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])

(…) We get a more practical implementation of RFC 2822 if we omit the syntax using double quotes and square brackets. It will still match 99.99% of all email addresses in actual use today.

[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?

A further change you could make is to allow any two-letter country code top level domain, and only specific generic top level domains. This regex filters dummy email addresses like [email protected]. You will need to update it as new top-level domains are added.

[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+(?:[A-Z]{2}|com|org|net|gov|mil|biz|info|mobi|name|aero|jobs|museum)\b

So even when following official standards, there are still trade-offs to be made. Don’t blindly copy regular expressions from online libraries or discussion forums. Always test them on your own data and with your own applications.

Emphasis mine

Answer:

Wow, there are lots of complexity here. If all you want to do is just catch the most obvious syntax errors, I would do something like this:

^\[email protected]\S+$

It usually catches the most obvious errors that the user makes and assures that the form is mostly right, which is what JavaScript validation is all about.

Answer:

There’s something you have to understand the second you decide to use a regular expression to validate emails: It’s probably not a good idea. Once you have come to terms with that, there are many implementations out there that can get you halfway there, this article sums them up nicely.

In short, however, the only way to be absolutely, positively sure that what the user entered is in fact an email is to actually send an email and see what happens. Other than that it’s all just guesses.

Answer:

HTML5 itself has email validation. If your browser supports HTML5 then you can use the following code.

<form><input type="email" placeholder="[email protected]" required>
    <input type="submit">
</form>

jsFiddle link

From the HTML5 spec:

A valid e-mail address is a string that matches the email production of the following ABNF, the character set for which is Unicode.

email   = 1*( atext / "." ) "@" label *( "." label )
label   = let-dig [ [ ldh-str ] let-dig ]  ; limited to a length of 63 characters by RFC 1034 section 3.5
atext   = < as defined in RFC 5322 section 3.2.3 >
let-dig = < as defined in RFC 1034 section 3.5 >
ldh-str = < as defined in RFC 1034 section 3.5 >

This requirement is a willful violation of RFC 5322, which defines a syntax for e-mail addresses that is simultaneously too strict (before the “@” character), too vague (after the “@” character), and too lax (allowing comments, whitespace characters, and quoted strings in manners unfamiliar to most users) to be of practical use here.

The following JavaScript- and Perl-compatible regular expression is an implementation of the above definition.

/^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-][email protected][a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$/

Answer:

I have found this to be the best solution:

/^[^\[email protected]][email protected][^\[email protected]]+\.[^\[email protected]]+$/

It allows the following formats:

1.  [email protected]
2.  [email protected]
3.  [email protected]
4.  [email protected]
9.  #!$%&'*+-/=?^_`{}|[email protected]
6.  "()[]:,;@\\"!#$%&'*+-/=?^_`{}| ~.a"@example.org
7.  " "@example.org (space between the quotes)
8.  üñîçøðé@example.com (Unicode characters in local part)
9.  üñîçøðé@üñîçøðé.com (Unicode characters in domain part)
10. Pelé@example.com (Latin)
11. δοκιμή@παράδειγμα.δοκιμή (Greek)
12. 我買@屋企.香港 (Chinese)
13. 甲斐@黒川.日本 (Japanese)
14. чебурашка@ящик-с-апельсинами.рф (Cyrillic)

It’s clearly versatile and allows the all-important international characters, while still enforcing the basic [email protected] format. It will block spaces which are technically allowed by RFC, but they are so rare that I’m happy to do this.

Answer:

In modern browsers you can build on top of @Sushil’s answer with pure JavaScript and the DOM:

function validateEmail(value) {
  var input = document.createElement('input');

  input.type = 'email';
  input.required = true;
  input.value = value;

  return typeof input.checkValidity === 'function' ? input.checkValidity() : /\[email protected]\S+\.\S+/.test(value);
}

I’ve put together an example in the fiddle http://jsfiddle.net/boldewyn/2b6d5/. Combined with feature detection and the bare-bones validation from Squirtle’s Answer, it frees you from the regular expression massacre and does not bork on old browsers.

Answer:

This is the correct RFC822 version.

function checkEmail(emailAddress) {
  var sQtext = '[^\x0d\x22\x5c\x80-\xff]';
  var sDtext = '[^\x0d\x5b-\x5d\x80-\xff]';
  var sAtom = '[^\x00-\x20\x22\x28\x29\x2c\x2e\x3a-\x3c\x3e\x40\x5b-\x5d\x7f-\xff]+';
  var sQuotedPair = '\x5c[\x00-\x7f]';
  var sDomainLiteral = '\x5b(' + sDtext + '|' + sQuotedPair + ')*\x5d';
  var sQuotedString = '\x22(' + sQtext + '|' + sQuotedPair + ')*\x22';
  var sDomain_ref = sAtom;
  var sSubDomain = '(' + sDomain_ref + '|' + sDomainLiteral + ')';
  var sWord = '(' + sAtom + '|' + sQuotedString + ')';
  var sDomain = sSubDomain + '(\x2e' + sSubDomain + ')*';
  var sLocalPart = sWord + '(\x2e' + sWord + ')*';
  var sAddrSpec = sLocalPart + '\x40' + sDomain; // complete RFC822 email address spec
  var sValidEmail = '^' + sAddrSpec + '$'; // as whole string

  var reValidEmail = new RegExp(sValidEmail);

  return reValidEmail.test(emailAddress);
}

Answer:

JavaScript can match a regular expression:

emailAddress.match( / some_regex /);

Here’s an RFC22 regular expression for emails:

^((?>[a-zA-Z\d!#$%&'*+\-/=?^_`{|}~]+\x20*|"((?=[\x01-\x7f])[^"\]|\[\x01-\x7f])*
"\x20*)*(?<angle><))?((?!\.)(?>\.?[a-zA-Z\d!#$%&'*+\-/=?^_`{|}~]+)+|"((?=[\x01-\x
7f])[^"\]|\[\x01-\x7f])*")@(((?!-)[a-zA-Z\d\-]+(?<!-)\.)+[a-zA-Z]{2,}|\[(((?(?<
!\[)\.)(25[0-5]|2[0-4]\d|[01]?\d?\d)){4}|[a-zA-Z\d\-]*[a-zA-Z\d]:((?=[\x01-\x7f])
[^\\[\]]|\[\x01-\x7f])+)\])(?(angle)>)$

Answer:

All email addresses contain an ‘at’ (i.e. @) symbol. Test that necessary condition:

email.indexOf("@") > 0

Don’t bother with anything more complicated. Even if you could perfectly determine whether an email is RFC-syntactically valid, that wouldn’t tell you whether it belongs to the person who supplied it. That’s what really matters.

To test that, send a validation message.

Answer:

Correct validation of email address in compliance with the RFCs is not something that can be achieved with a one-liner regular expression. An article with the best solution I’ve found in PHP is What is a valid email address?. Obviously, it has been ported to Java. I think the function is too complex to be ported and used in JavaScript. JavaScript/node.js port: https://www.npmjs.com/package/email-addresses.

A good practice is to validate your data on the client, but double-check the validation on the server. With this in mind, you can simply check whether a string looks like a valid email address on the client and perform the strict check on the server.

Here’s the JavaScript function I use to check if a string looks like a valid mail address:

function looksLikeMail(str) {
    var lastAtPos = str.lastIndexOf('@');
    var lastDotPos = str.lastIndexOf('.');
    return (lastAtPos < lastDotPos && lastAtPos > 0 && str.indexOf('@@') == -1 && lastDotPos > 2 && (str.length - lastDotPos) > 2);
}

Explanation:

  • lastAtPos < lastDotPos: Last @ should be before last . since @ cannot be part of server name (as far as I know).

  • lastAtPos > 0: There should be something (the email username) before the last @.

  • str.indexOf('@@') == -1: There should be no @@ in the address. Even if @ appears as the last character in email username, it has to be quoted so " would be between that @ and the last @ in the address.

  • lastDotPos > 2: There should be at least three characters before the last dot, for example [email protected].

  • (str.length - lastDotPos) > 2: There should be enough characters after the last dot to form a two-character domain. I’m not sure if the brackets are necessary.

Answer:

This was stolen from http://codesnippets.joyent.com/posts/show/1917

email = $('email');
filter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
if (filter.test(email.value)) {
  // Yay! valid
  return true;
}
else
  {return false;}

Answer:

Do this:

[a-zA-Z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-zA-Z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?\.)+[a-zA-Z0-9](?:[a-zA-Z0-9-]*[a-zA-Z0-9])?

Why? It’s based on RFC 2822, which is a standard ALL email addresses MUST adhere to. And I’m not sure why you’d bother with something “simpler”… you’re gonna copy and paste it anyway 😉

Often when storing email addresses in the database I make them lowercase and, in practice, regexs can usually be marked case insensitive. In those cases this is slightly shorter:

[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?

Here’s an example of it being used in JavaScript (with the case insensitive flag i at the end).

var emailCheck=/^[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?$/i;
console.log( emailCheck.test('[email protected]') );

Note:
Technically some emails can include quotes in the section before the @ symbol with escape characters inside the quotes (so your email user can be obnoxious and contain stuff like @ and "..." as long as it’s written in quotes). NOBODY DOES THIS EVER! It’s obsolete. But, it IS included in the true RFC 2822 standard, and omitted here.

More info: http://www.regular-expressions.info/email.html

Answer:

I’m really looking forward to solve this problem.
So I modified email validation regular expression above

to pass the examples in Wikipedia Email Address.

And you can see the result in here.

enter image description here

Answer:

Simply check out if the entered email address is valid or not using HTML.

<input type="email"/>

There isn’t any need to write a function for validation.

Answer:

You should not use regular expressions to validate an input string to check if it’s an email. It’s too complicated and would not cover all the cases.

Now since you can only cover 90% of the cases, write something like:

function isPossiblyValidEmail(txt) {
   return txt.length > 5 && txt.indexOf('@')>0;
}

You can refine it. For instance, ‘[email protected]’ is valid. But overall you get the gist. And don’t get carried away… A simple 90% solution is better than 100% solution that does not work.

The world needs simpler code…

Answer:

This is how node-validator does it:

/^(?:[\w\!\#$\%\&\'\*\+\-\/\=\?\^\`\{\|\}\~]+\.)*[\w\!\#$\%\&\'\*\+\-\/\=\?\^\`\{\|\}\~][email protected](?:(?:(?:[a-zA-Z0-9](?:[a-zA-Z0-9\-](?!\.)){0,61}[a-zA-Z0-9]?\.)+[a-zA-Z0-9](?:[a-zA-Z0-9\-](?!$)){0,61}[a-zA-Z0-9]?)|(?:\[(?:(?:[01]?\d{1,2}|2[0-4]\d|25[0-5])\.){3}(?:[01]?\d{1,2}|2[0-4]\d|25[0-5])\]))$/

Answer:

It’s hard to get an email validator 100% correct. The only real way to get it correct would be to send a test email to the account. That said, there are a few basic checks that can help make sure that you’re getting something reasonable.

Some things to improve:

Instead of new RegExp, just try writing the regexp out like this:

if (reg.test(/@/))

Second, check to make sure that a period comes after the @ sign, and make sure that there are characters between the @s and periods.

Answer:

Use this code inside your validator function:

var emailID = document.forms["formName"]["form element id"].value;
atpos = emailID.indexOf("@");
dotpos = emailID.lastIndexOf(".");
if (atpos < 1 || ( dotpos - atpos < 2 ))
{
    alert("Please enter correct email ID")
    return false;
}

Else you can use jQuery. Inside rules define:

eMailId: {
    required: true,
    email: true
}

Answer:

Regex update 2018! try this

let val = '[email protected]';
if(/^[a-z0-9][a-z0-9-_\.][email protected]([a-z]|[a-z0-9]?[a-z0-9-]+[a-z0-9])\.[a-z0-9]{2,10}(?:\.[a-z]{2,10})?$/.test(val)) {
   console.log('passed');
}

typscript version complete

//
export const emailValid = (val:string):boolean => /^[a-z0-9][a-z0-9-_\.][email protected]([a-z]|[a-z0-9]?[a-z0-9-]+[a-z0-9])\.[a-z0-9]{2,10}(?:\.[a-z]{2,10})?$/.test(val);

more info https://git.io/vhEfc

Answer:

A solution that does not check the existence of the TLD is incomplete.

Almost all answers to this questions suggest using Regex to validate emails addresses. I think Regex is only good for a rudimentary validation. It seems that the checking validation of email addresses is actually two separate problems:

1- Validation of email format: Making sure if the email complies with the format and pattern of emails in RFC 5322 and if the TLD actually exists. A list of all valid TLDs can be found here.

For example, although the address [email protected] will pass the regex, it is not a valid email, because ccc is not a top-level domain by IANA.

2- Making sure the email actually exists: For doing this, the only option is to send the users an email.

Answer:

Regex for validating email address

[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])+

Answer:

Here is a very good discussion about using regular expressions to validate email addresses; “Comparing E-mail Address Validating Regular Expressions

Here is the current top expression, that is JavaScript compatible, for reference purposes:

/^[-a-z0-9~!$%^&*_=+}{\'?]+(\.[-a-z0-9~!$%^&*_=+}{\'?]+)*@([a-z0-9_][-a-z0-9_]*(\.[-a-z0-9_]+)*\.(aero|arpa|biz|com|coop|edu|gov|info|int|mil|museum|name|net|org|pro|travel|mobi|[a-z][a-z])|([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}))(:[0-9]{1,5})?$/i

Answer:

Apparently, that’s it:

/^([\w\!\#$\%\&\'\*\+\-\/\=\?\^\`{\|\}\~]+\.)*[\w\!\#$\%\&\'\*\+\-\/\=\?\^\`{\|\}\~][email protected]((((([a-z0-9]{1}[a-z0-9\-]{0,62}[a-z0-9]{1})|[a-z])\.)+[a-z]{2,6})|(\d{1,3}\.){3}\d{1,3}(\:\d{1,5})?)$/i

Taken from http://fightingforalostcause.net/misc/2006/compare-email-regex.php on Oct 1 ’10.

But, of course, that’s ignoring internationalization.

Answer:

In contrast to squirtle, here is a complex solution, but it does a mighty fine job of validating emails properly:

function isEmail(email) { 
    return /^((([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);
} 

Use like so:

if (isEmail('[email protected]')){ console.log('This is email is valid'); }

Answer:

My knowledge of regular expressions is not that good. That’s why I check the general syntax with a simple regular expression first and check more specific options with other functions afterwards. This may not be not the best technical solution, but this way I’m way more flexible and faster.

The most common errors I’ve come across are spaces (especially at the beginning and end) and occasionally a double dot.

function check_email(val){
    if(!val.match(/\[email protected]\S+\.\S+/)){ // Jaymon's / Squirtle's solution
        // Do something
        return false;
    }
    if( val.indexOf(' ')!=-1 || val.indexOf('..')!=-1){
        // Do something
        return false;
    }
    return true;
}

check_email('[email protected]'); // Returns false
check_email('[email protected]'); // Returns false
check_email(' [email protected]'); // Returns false
check_email('[email protected]'); // Returns true

Answer:

<form name="validation" onSubmit="return checkbae()">
    Please input a valid email address:<br />

    <input type="text" size=18 name="emailcheck">
    <input type="submit" value="Submit">
</form>

<script language="JavaScript1.2">
    var testresults
    function checkemail(){
        var str = document.validation.emailcheck.value
        var filter = /^([\w-]+(?:\.[\w-]+)*)@((?:[\w-]+\.)*\w[\w-]{0,66})\.([a-z]{2,6}(?:\.[a-z]{2})?)$/i
        if (filter.test(str))
            testresults = true
        else {
            alert("Please input a valid email address!")
            testresults = false
        }
        return (testresults)
    }
</script>

<script>
    function checkbae(){
        if (document.layers || document.getElementById || document.all)
            return checkemail()
        else
            return true
    }
</script>

Answer:

The regular expression provided by Microsoft within ASP.NET MVC is

/^[\w-]+(\.[\w-]+)*@([a-z0-9-]+(\.[a-z0-9-]+)*?\.[a-z]{2,6}|(\d{1,3}\.){3}\d{1,3})(:\d{4})?$/

Which I post here in case it’s flawed – though it’s always been perfect for my needs.

Answer:

Wikipedia standard mail syntax :

https://en.wikipedia.org/wiki/Email_address#Examples
https://fr.wikipedia.org/wiki/Adresse_%C3%A9lectronique#Syntaxe_exacte

function validMail(mail)
{
    return /^(([^<>()\[\]\.,;:\[email protected]\"]+(\.[^<>()\[\]\.,;:\[email protected]\"]+)*)|(\".+\"))@(([^<>()\.,;\[email protected]\"]+\.{0,1})+([^<>()\.,;:\[email protected]\"]{2,}|[\d\.]+))$/.test(mail);
}

// VALID MAILS

validMail('[email protected]') // Return true
validMail('[email protected]') // Return true
validMail('[email protected]') // Return true
validMail('[email protected]') // Return true
validMail('[email protected]') // Return true
validMail('user+mailbox/[email protected]') // Return true
validMail('"very.(),:;<>[]\".VERY.\"[email protected]\ \"very\".unusual"@strange.example.com') // Return true
validMail('!#$%&\'*+-/=?^_`.{|}[email protected]') // Return true
validMail('"()<>[]:,;@\\"!#$%&\'-/=?^_`{}| ~.a"@example.org') // Return true
validMail('"[email protected]"@example.com') // Return true
validMail('"Fred Bloggs"@example.com') // Return true
validMail('"Joe.\Blow"@example.com') // Return true
validMail('Loïc.Accentué@voilà.fr') // Return true
validMail('" "@example.org') // Return true
validMail('[email protected][IPv6:2001:DB8::1]') // Return true

// INVALID MAILS

validMail('Abc.example.com') // Return false
validMail('[email protected]@[email protected]') // Return false
validMail('a"b(c)d,e:f;g<h>i[j\k][email protected]') // Return false
validMail('just"not"[email protected]') // Return false
validMail('this is"not\[email protected]') // Return false
validMail('this\ still\"not\[email protected]') // Return false
validMail('[email protected]') // Return false
validMail('[email protected]') // Return false

Show this test : https://regex101.com/r/LHJ9gU/1