[Mailman-Users] mbox + references field

[Mark Sapiro]

Jean-Philippe GIOLA wrote:
>
>In the mailman mbox archives, there is sometimes a "References" field 
>for mails.
>Why does this field not present for all mails ???
>when I say "present", I mean "present" for all answer to mails.
>I understand very weel that the first mail of a new thread can't have a 
>reference field.

References: and In-Reply-To: headers are optional and are added to a
reply by the sender's MUA. Any particular MUA will add one, the other,
both or neither, although RFC 2822 says

   Though optional, every message SHOULD have a "Message-ID:" field.
   Furthermore, reply messages SHOULD have "In-Reply-To:" and
   "References:" fields as appropriate, as described below.

(section 3.6.4).

--
Mark Sapiro <msapiro at value.net>       The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan