This function attempts to extract mailing addresses from the string passed
to #new. The function returns an RMail::Address::List of RMail::Address objects (RMail::Address::List is a subclass of Array). A
malformed input string will not generate an exception. Instead, the array
returned will simply not contained the malformed addresses.
The string is expected to be in a valid format as documented in
RFC2822’s mailbox-list grammar. This will work for lists of addresses
in the To:, From:, etc. headers in email.