https://en.wikipedia.org/wiki/Posting_style
维基百科 post sytle
When a message is replied to in e-mail, Internet forums, or Usenet, the original can often be included, or “quoted”, in a variety of different posting styles.
在email，internet 论坛或者usenet回复信息时，原始的邮件经常被通过各种邮件格式引用。
The main options are interleaved posting (also called inline replying, in which the different parts of the reply follow the relevant parts of the original post), bottom-posting (in which the reply follows the quote) or top-posting (in which the reply precedes the quoted original message). For each of those options, there is also the issue of whether trimming of the original text is allowed, required, or preferred.
主要的选择有
interleaved posting或者叫inline reply：紧跟原始邮件的相关部分回复不通的部分。
bottom post：在引用之后回复。
top post：在引入原始邮件之前回复
对应这些选择，是否允许、需要或者说优先修改原始的文件，这是一个问题。
For a long time the traditional style was to post the answer below as much of the quoted original as was necessary to understand the reply (bottom or inline). Many years later, when email became widespread in business communication, it became a widespread practice to reply above the entire original and leave it (supposedly untouched) below the reply.
很长一段时间，在引用原始文件之后回复邮件这种传统方式（bottom或者inline）被认为有利于理解。多年之后，随着email成为商业交流的主流，在全部原始邮件之上回复，把原始未改变的邮件反正回复之后成为了惯例。
While each online community differs on which styles are appropriate or acceptable, within some communities the use of the “wrong” method risks being seen as a breach of netiquette, and can provoke vehement response from community regulars.
然而每个在线社团的风格都不一样，一些社区使用错误方式可能被认为有失网络礼仪，并且可能引起社团大部分人的强烈不满。
Quoting previous messages
In an e-mail reply, it is sometimes appropriate to include a full or partial copy of the original message that is being replied to. As opposed to in-person conversations and Internet chats, email responses may be received long after the original message was sent, so the original sender may have forgotten, misplaced or deleted the original. Many email reading programs (mail user agents) encourage this behaviour by automatically including a copy of the original message in the reply editing window.
回复email时，包含全部或者部分需要回复的原始信息是一种合适的做法。相对于个人交谈或者网络聊天，邮件是比较慢的，可能原始邮件已经发出很久了，才收到了回复邮件，原始邮件的发送人可能已经忘了或者删除了原始邮件。大部分邮件程序在回复编辑窗口会自动包含原始邮件的备份信息。
Quoted text from previous messages is usually distinguished in some way from the new (reply) text. At a minimum, the two parts are given different indentation. In the example below, the first line is the original message, the second line is the reply:
引用之前信息通常会和当前的回复区分开来。至少两部分会使用不同的缩进。就像下面的例子，第一行是原始信息，第二行是回复。
Alternatively, special delimiter lines may be used:
或者，使用特殊的分隔符
For extra clarity, blank lines may also be inserted between the two parts. When using an email medium that supports text markup (such as HTML or RTF), the previous text may be indicated by a distinctive font and/or color:
为了更清晰，在两部分之间会插入空行。如果使用了email支持text makrup（如果HTML货RTF），之前的文字会使用特殊字体或者颜色
Quoted line prefix
未完待续