Check the email address format code

This is a code that fully complies with RFC2822 and RFC2821. Check only the single email address.
Function check_email_address ($ email ){
// First, we check that there's one @ symbol, and that the lengths are right
If (! Ereg ("[^ @] {1,255} @ [^ @] {}", $ email )){
// Email invalid because wrong number of characters in one section, or wrong number of @ symbols.
Return false;
}
// Split it into sections to make life easier
$ Email_array = explode ("@", $ email );
$ Local_array = explode (".", $ email_array [0]);
For ($ I = 0; $ I <sizeof ($ local_array); $ I ++ ){
If (! Ereg ("^ ([A-Za-z0-9! # $ % & '* +/=? ^ _ '{| }~ -] [A-Za-z0-9! # $ % & '* +/=? ^ _ '{| }~. -] {0, 63}) | ("[^ (|")] {0, 62} ") $", $ local_array [$ I]) {
Return false;
}
}
If (! Ereg ("^ [? [0-9.] +]? $ ", $ Email_array [1]) {// Check if domain is IP. If not, it shoshould be valid domain name
$ Domain_array = explode (".", $ email_array [1]);
If (sizeof ($ domain_array) <2 ){
Return false; // Not enough parts to domain
}
For ($ I = 0; $ I <sizeof ($ domain_array); $ I ++ ){
If (! Ereg ("^ ([A-Za-z0-9] [A-Za-z0-9-] {} [A-Za-z0-9]) | ([A-Za-z0-9] +) $", $ domain_array [$ I]) {
Return false;
}
}
}
Return true;
}
RFC2822: defines the email format
Http://www.faqs.org/rfcs/rfc2822.html
RFC2821: defines the maximum length of the username and server name before and after @ In the email, section 4.5.3.1
Http://www.faqs.org/rfcs/rfc2821.html
In addition, RFC2234 defines ABNF and some commonly used terminal:
Http://www.faqs.org/rfcs/rfc2234.html
Most email address check codes on the Internet are not written in accordance with these RFC.
You can also add code to check whether the email server exists. This is available on the Internet.