To determine where a message is to go, the following algorithm is used by default.
A reply is when you want to respond just to the person who sent the message via mail. There will only be one recipient. To determine who the recipient will be, the following headers are consulted, in turn:
A wide reply is a mail response that includes all entities
mentioned in the message you are responding to. All mailboxes from the
following headers will be concatenated to form the outgoing
(unless there’s a
Reply-To, in which case that is used instead).
Mail-Copies-To header is present, it will also be included
in the list of mailboxes. If this header is ‘never’, that means
Reply-To) mailbox will be suppressed.
A followup is a response sent via news. The following headers (listed in order of precedence) determine where the response is to be sent:
Mail-Copies-To header is present, it will be used as the
basis of the new
Cc header, except if this header is