Updating old Functions to run with PHP 7.2

I've configured a new vps with Ubuntu 18.04 and now want to transfer websites running on my old vps running Ubuntu 14.04.6 LTS (GNU/Linux 3.13.0-153-generic x86_64).
I have a functions include for checking email addresses - see below
I have installed PEAR Validate and Mail packages.
I call the function with:
$email=$_POST['email'];
if(!emailaddresscheck($email)){
$error[]="Your email address appears to be invalid..";
}

I have tried replacing occurrences of eregi with preg_match()

Any guidance on how to adapt the code to run with PHP 7.2 would be very much appreciated.
dbg1991
#####################################################

Code:

<?php
#check for format and domain existence using PEAR - returns true or false
function emailcheck($email){
require_once 'Validate.php';
if (Validate::email($email, array('check_domain' => 'true'))) {
    return true;
}else{
        return false;
        }
}

# formats string for html output - returns string formatted
function formatting(&$string){
$string=htmlspecialchars($string, ENT_QUOTES );
$string=str_ireplace("\r","",$string);
$string=str_ireplace("\n","<br />",$string);
$string=str_ireplace("","<strong>",$string);
$string=str_ireplace("[eb]","</strong>",$string);

$string=stripslashes($string);
$string=str_replace("'","&acute;",$string);
$string=str_ireplace("[l]","<span class=\"large\">",$string);
$string=str_ireplace("[el]","</span>",$string);


}

# formats HTML strings for text email output - returns string formatted
function emailformat(&$string){
$string=str_ireplace("<b>","",$string);
$string=str_ireplace("</b>","",$string);
$string=str_ireplace("<strong>","",$string);
$string=str_ireplace("</strong>","",$string);
$string=str_ireplace("<br />","\n",$string);
$string=str_replace("&acute;","'",$string);
}



# checks for email address in correct form and to valid domain - returns true or flase
function emailaddresscheck($emailaddress){
$validemailaddress="^[0-9a-z~!#$%&_-]([.]?[0-9a-z~!#$%&_-])*" ."@[0-9a-z~!#$%&_-]([.]?[0-9a-z~!#$%&_-])*$";
if(!eregi($validemailaddress,$emailaddress)){return false;}
list($username, $maildomain)=split("@", $emailaddress);
if(checkdnsrr($maildomain,"MX")){return true;}
return false;
}
function myCheckDNSRR($hostName, $recType = '')
{
        if(!empty($hostName)) {
                if( $recType == '' ) $recType = "MX";
                exec("nslookup -type=$recType $hostName", $result);
                // check each line to find the one that starts with the host
                // name. If it exists then the function succeeded.
                foreach ($result as $line) {
                        if(eregi("^$hostName",$line)) {
                                return true;
                        }
                }
                // otherwise there was no mail handler for the domain
                return false;
        }
        return false;
}
?>

 

Please use [ code ]your code[ /code ] without the space inside the bracket, otherwise we can't read your code properly.

 

Done. Thanks ahrasis for educating a novice in forum posting.

 

OK I think I've fixed it. After much head scratching I've come up with:

Code:

<?php
#check for format and domain existence
function emailchecker($email){
        $findme="@";
        $pos=strpos($email, $findme);
        if(!$pos){
                return false;
                }else{
                $parts = explode("@",$email);
                $username = $parts[1];
                $username = "$username.";
                if(!checkdnsrr (  $username , "MX"  )){
                return false;
                }else{
                return true;
                }
        }

}
////////////Function call////////////////////////////////////////////////
//$email="";
//$return=emailchecker($email);
//if(!$return){
//echo "<p>$email probably false $return  </p>";
//}else{
//echo "<p>$email seems OK</p>";
//}
/////////////////////////////////////////////////////////////////////////////

# formats string for html output - returns string formatted
function formatting(&$string){
$string=htmlspecialchars($string, ENT_QUOTES );
$string=str_ireplace("\r","",$string);
$string=str_ireplace("\n","<br />",$string);
$string=str_ireplace("[b]","<strong>",$string);
$string=str_ireplace("[eb]","</strong>",$string);

$string=stripslashes($string);
$string=str_replace("'","&acute;",$string);
$string=str_ireplace("[l]","<span class=\"large\">",$string);
$string=str_ireplace("[el]","</span>",$string);
}

# formats HTML strings for text email output - returns string formatted
function emailformat(&$string){
$string=str_ireplace("<b>","",$string);
$string=str_ireplace("</b>","",$string);
$string=str_ireplace("<strong>","",$string);
$string=str_ireplace("</strong>","",$string);
$string=str_ireplace("<br />","\n",$string);
$string=str_replace("&acute;","'",$string);
}
?>