function VerificationMail(email)
{
 address = email.toUpperCase();

  if(address.length < 5)
     return false;

  if(address.indexOf("..") != -1) 
     return false;

  for(i=0; i<address.length; i++)
  {
     tmpchar = address[i];

     if((tmpchar != '.') && (tmpchar != '@')
		&& ( (tmpchar <  '0') || (tmpchar  > '9') )
		&& ( (tmpchar <  'A') || (tmpchar  > 'Z') )
		&& ( (tmpchar <  '-') || (tmpchar  > '-') ) 
		&& ( (tmpchar <  '_') || (tmpchar  > '_') ) )
        return false;
  }


  if(address.indexOf('@') == -1)
     return false;

  if(address.indexOf('.') == -1)
     return false;

  if( (address.substring(0, 1) == '@') || (address.substring(0, 1) == '.') )
     return false;

  if( (address.substring(address.length -1, address.length) == '@') || (address.substring(address.length -1, address.length) == '.'))
     return false;

  if(address.indexOf('@', address.indexOf('@', 0) + 1) != -1)
     return false;

  if(address.substring(address.indexOf('@') + 1, address.indexOf('@') +2) == '.')
     return false;

  if(address.substring(address.indexOf('@') - 1, address.indexOf('@')) == '.')
     return false;

  // address may be ok
  return true;
}


function verification_contact()
{

if (document.contacta.raison.value.length < 3) // prénom
{
alert("veuillez saisir votre non ");
return false;
}

else if( ! VerificationMail( document.contacta.email.value) ) // email
{
alert("veuillez saisir une Adresse Mail valide");
return false;
}

else if (document.contacta.message.value.length < 3)  //login
{
alert("veuillez saisir votre message");
return false;
}

else 

return true;
}