Question

虽然the RFC 2045明确指出引用可打印（QP）中的行不得超过76个字符，但在现实世界中并非每个客户端都遵循此要求。或者我是否误解了RFC的要求？

考虑来自真实世界邮件的以下几行：

<style type=3D"text/css">=0Abody,td { color:#2f2f2f; font:11px/1.35em Verdana, Arial, Helvetica, sans-serif; }=0A</style>=0A<body style=3D"background:#F6F6F6; font-family:Verdana, Arial, Helvetica, sa=
ns-serif; font-size:12px; margin:0; padding:0;">=0D=0A<div style=3D"background:#F6F6F6; font-family:Verdana, Arial, Helvetica, sans-serif; font-size:12px; margin:0; padding:0;">=0D=0A<table cellspacin=
g=3D"0" cellpadding=3D"0" border=3D"0" width=3D"100%">=0D=0A<tr>=0D=0A    <td align=3D"center" valign=3D"top" style=3D"padding:20px 0 20px 0">=0D=0A        <!-- [ header starts here] -->=0D=0A       =

每行是201个字符加上CRLF。但是，有几个=0A序列转换为LF。那么这是否意味着我需要能够解析这条消息，还是我可以拒绝它？

在我看来，它违反了RFC的以下声明，但我并非100％肯定：

(5)   (Soft Line Breaks) The Quoted-Printable encoding
      REQUIRES that encoded lines be no more than 76
      characters long.  If longer lines are to be encoded
      with the Quoted-Printable encoding, "soft" line breaks
      must be used.  An equal sign as the last character on a
      encoded line indicates such a non-significant ("soft")
      line break in the encoded text.

Answer 1

尽管最长的行包含128个符号，但您应该能够解析此消息。

此邮件中有=0A和=SPACE个序列 =0A是一个有意义的换行符，=SPACE是一个软换行符硬换行应为CRLF（=0D=0A），但链接的RFC 2045为也只允许LF（没有CR）：

(4)   (Line Breaks) A line break in a text body, represented
      as a CRLF sequence in the text canonical form, must be
      represented by a (RFC 822) line break, which is also a
      CRLF sequence, in the Quoted-Printable encoding.  (...)

      Note that many implementations may elect to encode the
      local representation of various content types directly
      rather than converting to canonical form first,
      encoding, and then converting back to local
      representation.  In particular, this may apply to plain
      text material on systems that use newline conventions
      other than a CRLF terminator sequence.  Such an
      implementation optimization is permissible, but only
      when the combined canonicalization-encoding step is
      equivalent to performing the three steps separately.

在quoted-printable中，根据76个字符规则，什么构成换行符？

1 个答案: