Send to multiple recipients

What is the fastest way to send to multiple recipients in Mac Mail -
Using the To: field

I would expect to add a comma after the first address is entered - and then it is prepared for a second address. But this doesn't work.

The only thing I could figure out was dragging addresses over from the addressbook.

of course I'd figure it out right after I post
don't use a comma
Mac Mail will insert the comma for you

Thanks for the swift replies

It seems to recognize an address once it is typed and then inserts a comma if you click into the field again

this is how it is in Leopard anyway (when I started)