Did you know that php has its own method to verify whether the email address exists?

There are many ways to verify email addresses in PHP. The more commonly used one is regular expression, but regular expressions are troublesome. There is a built-in method in PHP that can verify email addresses. Below Let’s give a detailed introduction, let’s take a look together

My PHP comes with its own method for verification.

filter_var

filter_var is a variable filtering method built into PHP, which provides many practical Filter can be used to verify integers, floating point numbers, email addresses, URLs, MAC addresses, etc.

If filter_var returns false,

$email = "lastchiliarch@163.com";
 
var_dump(filter_var($email, FILTER_VALIDATE_EMAIL));
 
 
$email = "asb";
var_dump(filter_var($email, FILTER_VALIDATE_EMAIL));
 
$email = "1@a.com";
var_dump(filter_var($email, FILTER_VALIDATE_EMAIL));

Output:

string(21) "lastchiliarch@163.com"
bool(false)
string(7) 1@a.com

For the illegal email format asb, false is returned, but for 1@a.com, it passes, still Slightly flawed.

However, if the general rules are passed, 1@a.com will be considered to be a legitimate email address. So is there any way to verify it more accurately?

checkdnsrr

checkdnsrr is actually used to query the DNS record of the specified host. We can use it to verify whether the mailbox exists.

For 1@a.com, the MX record definitely does not exist.

$email = "lastchiliarch@163.com";
  var_dump(checkdnsrr(array_pop(explode("@",$email)),"MX"));
  $email = "1@a.com";
  var_dump(checkdnsrr(array_pop(explode("@",$email)),"MX"));

Output:

  bool(true)
  bool(false)

As you can see, it is perfect. The only drawback is that it is too slow. After all, it is a network request. Therefore, it is not suitable to use this method to verify a large number of mailboxes simultaneously.

filter_var+checkdnsrr

We can combine filter_var and checkdnsrr for verification. For most illegal mailboxes, filter_var will definitely be used. It hangs up, and you can use

checkdnsrr to further judge the rest.

$email_arr = array("lastchiliarch@163.com", "1@a.com");
  foreach($email_arr as $email) {
    if (filter_var($email) === false) {
      echo "invalid email: $email \n";
      continue;
    }
 
    if(checkdnsrr(array_pop(explode("@",$email)),"MX") === false) {
      echo "invalid email: $email \n";
      continue;
    }
  }

Output:

invalid email: 1@a.com

But it should be noted that since it is only checking the MX record, it can only be judged that 163.com exists, but it does not mean that the user lastchiliarch exists.

If you want to more accurately determine the existence of the mailbox, you can only connect to the SMTP server to verify it.

Introduced Email Verification, how PHP comes with its own method to verify whether the email, URL, and IP are legal. Here is an introduction:

Mainly uses filter_var function.

Syntax
filter_var(variable, filter, options)
variable Required. Specifies the variables to filter.
filter Optional. Specifies the ID of the filter to use.
options Specifies an array containing flags/options. Check the possible flags and options for each filter.

PHP Filters

Example #1 A filter_var() example

<?php

var_dump(filter_var(&#39;bob@example.com&#39;, FILTER_VALIDATE_EMAIL));

var_dump(filter_var(&#39;http://example.com&#39;, FILTER_VALIDATE_URL, FILTER_FLAG_PATH_REQUIRED));

?>

The above routine will output:

string(15) "bob@example.com"
bool(false)

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