A message received via a distribution list will have special values in the From: and To: fields of the message header.
The From: address will be a virtual email address of the member sending the message, using the their first and last names, and ending with @tvgarden.club
From: Arthur Gidlow <firstname.lastname@example.org>
This format helps smooth the way for message reception, as the tvgarden.club system is the correct system for messages originating from email@example.com addresses.
Although a virtual address, it is possible for the recipient to send a reply in the usual manner. The tvgarden.club system will take care of forwarding the reply to the correct 'real' address of the member who sent the original message.
The To: address will contain the name and address of the distribution list.
To: Gardening Club members <firstname.lastname@example.org>
This shows clearly that the message was sent to a distribution list, and not sent to an individual member.