use Mail::POP3Client;

$pop = new Mail::POP3Client(
    USER      => "username",    
    PASSWORD  => "password",
    HOST      => "server.domain.tld",
    AUTH_MODE => "PASS",           
    DEBUG     => 1      
);
$MailState = $pop->State;
if ( $MailState eq 'AUTHORIZATION' ) {
    die "\n\nBad user name or password!\n";
}
elsif ( $MailState eq 'DEAD' ) {
    die "\n\nMail server unreachable or unavailable!\n";
}
 
$continue = "false";
until ( $continue = "true" ) {

...