Either way , Arnt you also supposed to have another webpage it takes you to after you click on the form button that says summit like 'your submission has been sent' or whatever .
Do you have PHP support on your server? If you are using your free ISP space then it is doubtful but if you are not it is possible in which case I can help you make your form send a submission on another page rather than "mailto"
Yes, 1&1 does have PHP support. You will be better off using that, as your email address will be server side so it's more secure (as long as you use a bad-strings list to check against input strings).
If you have php then thats good - but you also need some sort of method to prevent the spammer bots from using - and usually thats in the form of a image code .
You also need to prevent the spammers from doing something called email injection .
Unfortunatly i dont have the available time needed for detailed replys at the moment and while i'm happy to point you in the right direction i cant do the technical support thingy at the moment .
takeaway_checkout.php
clicking on submit would take you to takeaway_checkout_do.php
Right as you have PHP this will be a lot easier for you, and will also prevent against spamming of your email address.
I see no reason to tell you here how to do it when there are plently of well written sites already showing it so instead I will link you to the best I have found