sub addressExists {
	
	my $address=shift @_; 
	
	my $sql = 'SELECT * FROM emails WHERE `email`=?';
	
		
    my $sth = $dbh->prepare( $sql );
		
 	$sth->execute($address);

	
}

##</code><code>##

#open connection

# some code here and then:

while (my $address=@address) {
 &addressExists($address);
# other stuff

}

#close connection