Define NAME as a mail alias that translates to DEFINITION.
This means that sending a message to NAME will actually send to DEFINITION.
Normally, the addresses in DEFINITION must be separated by commas.
If FROM-MAILRC-FILE is non-nil, then addresses in DEFINITION
can be separated by spaces; an address can contain spaces
if it is quoted with double-quotes.
(fn NAME DEFINITION &optional FROM-MAILRC-FILE)