PHP verifies the existence of e-mail address accurately

Background

PHP Check the e-mail address of a lot of methods, more commonly used is to write their own regular, but it is more troublesome, I have a method of PHP to do calibration.

Filter_var

Filter_var is a PHP built-in variable filtering method, provides a lot of practical filters, can be used to verify the integer, floating point, Mailbox, URL, MAC address and so on.

Specific filter Reference: Filters.validate

Filter_var If you return false, it means that the variable cannot pass through the filter, which is illegal.

$email = "lastchiliarch@163.com"; Var_dump (Filter_var ($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 (+) "lastchiliarch@163.com" bool (FALSE) string (7) "1@a.com"

For ASB This illegal mailbox format returned false, but for the 1@a.com passed, or slightly flawed ah.

But the general regular also through will think 1@a.com is a legal mailbox, then what method can be more accurate verification?

Checkdnsrr

CHECKDNSRR is actually used to query the DNS record of the specified host, and we can borrow it to verify that the mailbox exists.

For 1@a.com, the MX record must 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)

Can see, very perfect, the only drawback is too slow, after all, is to do a network request. So it is not appropriate to synchronize to a large number of mailboxes to use this practice to verify.

Filter_var+checkdnsrr

We can engage Filter_var and CHECKDNSRR do calibration, for the vast majority of illegal mailbox will certainly be in the Filter_var when the time to hang off, the rest of the use

CHECKDNSRR further judgment.

$email _arr = Array ("lastchiliarch@163.com", "1@a.com");    foreach ($email _arr as $email) {        if (Filter_var ($email) = = = False) {            echo "invalid email: $email \ n";            Continue;        }        if (CHECKDNSRR (Array_pop ("@", $email), "MX") = = = False) {            echo "invalid email: $email \ n";            Continue;        }    }   Output: Invalid email:1@a.com

However, it is important to note that because only the MX record is checked, it is only possible to judge that the 163.com is present, but it does not indicate that the Lastchiliarch user is present.

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

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