function mailvalidatie_nl() {
    var error = 0;
    var error_msg = "Het formulier is niet goed ingevuld.\n";
    var et = "@";
    var punt = ".";
    var str1 = document.contactformulier.naam.value;
    var str2 = document.contactformulier.mail.value;
    var str3 = document.contactformulier.bericht.value;
    
    if (str1 == "" ) 
        {
        error_msg += "\nU heeft uw naam niet ingevuld";
        error = 1;
    }
    if (str2 == "" || str2.indexOf(et) == -1 || str2.indexOf(et) == 0 || str2.indexOf(punt) == -1 || str2.indexOf(punt) == 0)
	{
        error_msg += "\nU heeft geen (geldig) mailadres ingevuld";
        error = 1;
    }
    if (str3 == "" ) 
        {
        error_msg += "\nHet berichtveld is leeg";
        error = 1;
    }
    if (error == 1)
        {
        window.alert(error_msg);    
        return false;
    }
}    

function mailvalidatie_en() {
    var error = 0;
    var error_msg = "This mailform cannot be send due to the following error.\n";
    var et="@";
    var punt=".";
    var str1 = document.contactformulier.naam.value;
    var str2 = document.contactformulier.mail.value;
    var str3 = document.contactformulier.bericht.value;
    
    if (str1 == "" ) 
        {
        error_msg += "\nYou did not enter your name";
        error = 1;
    }
    if (str2 == "" || str2.indexOf(et) == -1 || str2.indexOf(et) == 0 || str2.indexOf(punt) == -1 || str2.indexOf(punt) == 0)
	{
        error_msg += "\nYou did not enter a (valid) mailaddress";
        error = 1;
    }
    if (str3 == "" ) 
        {
        error_msg += "\nThe message-field is empty";
        error = 1;
    }
    if (error == 1)
        {
        window.alert(error_msg);    
        return false;
    }
}