福茲提克資訊科技網

考不考慮實作In-Reply-To: 和Reference: 這兩個欄位呢
個人是認為沒這兩個欄位
加上Message-ID:的用途實在不大
BBS上一向都是以「同標題」作為討論串的判別標準
往往內文已經離題了 但為了保持討論串 不能改標題
加上這兩個欄位可以讓文章的回覆關係更明顯
而且改標題討論串不會斷掉

Message-ID是「本篇文章的Message-ID」
In-Reply-To是「本篇文章回的那篇文章(parent)的Message-ID」
Reference則是「把整個討論串的Message-ID都留下來」
（如果以樹狀結構去看它，只有留從根走到該節點會經過的，分支不算）

RFC 2822:

   The "References:" field will contain the contents of the parent's

   "References:" field (if any) followed by the contents of the parent's

   "Message-ID:" field (if any).  If the parent message does not contain

   a "References:" field but does have an "In-Reply-To:" field

   containing a single message identifier, then the "References:" field

   will contain the contents of the parent's "In-Reply-To:" field

   followed by the contents of the parent's "Message-ID:" field (if

   any).  If the parent has none of the "References:", "In-Reply-To:",

   or "Message-ID:" fields, then the new message will have no

   "References:" field.