Currently when you are typing address in a new email and press Space it just expects you to continue typing. To actually complete the address you need to press Enter. Then it puts it into a "pill" that means address is completed, but focus moves to Subject field. So, when you have to enter multiple addresses it is constant pressing Enter, then press back into To field, type another address, press Enter, press back to To field. This jumping is unnecessary. There are no spaces in email addresses, so Space button should just auto-complete the address and it should then expect for another address to be typed in. Enter can still move you to the Subject field.