How Emails Are Addressed and Sent
When sending an email to a group you send it to the group address as follows.
|From:||John Doe <email@example.com>|
|To:||Our Book Club < firstname.lastname@example.org>|
|Subject:||October's Book Choice|
Gaggle Mail receives this message then looks up the group members and forwards it to them after changing a few of the fields. For example:
|From:||John Doe <bookclub+ email@example.com>|
|To:||Our Book Club <firstname.lastname@example.org>|
|Reply-To:||Our Book Club <email@example.com> or John Doe <firstname.lastname@example.org>|
|Subject:||[ Our Book Club] October's Book Choice|
Since the message is being sent by Gaggle Mail and to allow it to be signed with DKIM the From: address is changed to be that of a @gaggle.email domain.
A Reply-To header is added to the message which indicates the reply address used when the recipient selects 'Reply' from their email client. This address will either be the group address or the original sender's address depending on what option the "Replies are sent to:" setting is set to in the group administration panel.
The subject of the message is also updated to include the group name, this helps identify messages sent via the group. This can be disabled by changing the "Include group name in subject" setting in the administrator design sections.