从Outlook 7位编码处理电子邮件会在输出中引起有趣的字符
[英]Processing email from outlook 7bit encoding causes funny characters in output
问题描述
I am working on a project where I am building my own SMTP server. 
我正在开发自己的SMTP服务器的项目。 (please nobody ask why or provide me with things like Postfix, I have my reasons). （请问没人问为什么，或者给我提供Postfix之类的东西，我有我的理由）。
It is mostly working fine except with Outlook there seems to be some problem with encoding of the data that I am encoding from Outlook. 除了使用Outlook以外，其他大多数情况下都可以正常工作，但从Outlook编码的数据似乎似乎存在编码问题。
I keep getting content as follows: 我不断获得如下内容：
<html xmlns:v=3D"urn:schemas-microsoft-com:vml" =
xmlns:o=3D"urn:schemas-microsoft-com:office:office" =
xmlns:w=3D"urn:schemas-microsoft-com:office:word" =
Instead of: 代替：
<html xmlns:v="urn:schemas-microsoft-com:vml" =
xmlns:o="urn:schemas-microsoft-com:office:office" =
xmlns:w="urn:schemas-microsoft-com:office:word" =
Notice the 3D isn't there on the valid content. 请注意，有效内容上没有3D。
I have a function that listens to the socket for SMTP data which looks like the following: 我有一个函数可以监听套接字中的SMTP数据，如下所示：
if (stream.CanRead)
{
byte[] serverData = new byte[1024];
StringBuilder stringBuilder = new StringBuilder();
int numberOfBytesRead = 0;
do
{
numberOfBytesRead = stream.Read(serverData, 0, serverData.Length);
Encoding encoding = Encoding.GetEncoding("UTF-7", new FallbackEncoding(), new FallbackDecoding());
stringBuilder.AppendFormat("{0}", encoding.GetString(serverData, 0, numberOfBytesRead));
} while (stream.DataAvailable);
return stringBuilder.ToString();
In my FallbackDecoding function I have the following code 在我的FallbackDecoding函数中，我有以下代码
class FallbackDecoding : DecoderFallback
{
public override int MaxCharCount
{
get
{
return 1;
}
}
public override DecoderFallbackBuffer CreateFallbackBuffer()
{
return new Buffer();
}
private class Buffer : DecoderFallbackBuffer
{
private int _fallbackIndex;
private string _fallbackString;
public override int Remaining
{
get
{
return _fallbackString.Length - _fallbackIndex;
}
}
public override bool Fallback(byte[] bytesUnknown, int index)
{
byte unknownChar = bytesUnknown[index];
_fallbackString = Encoding.ASCII.GetString(new[] { (byte)(unknownChar & 127) });
_fallbackIndex = 0;
return true;
}
public override char GetNextChar()
{
if (Remaining > 0)
{
return _fallbackString[_fallbackIndex++];
}
else
{
return '\0';
}
}
public override bool MovePrevious()
{
if (_fallbackIndex > 0)
{
_fallbackIndex--;
return true;
}
return false;
}
}
For some reason the decoder fall back class is throwing an exception in the function public override bool Fallback . 出于某种原因，解码器后退类在public override bool Fallback函数中引发异常。 It throws an exception because bytesunknown only has 1 item in the array, but the index parameter is 128 so its throwing an index out of range exception but I have no idea why. 它会引发异常，因为bytesunknown在数组中只有1个项目，但是index参数是128，因此它抛出了索引超出范围的异常，但我不知道为什么。
I've tried changing ASCII to UTF-7 as Outlook sends the data in 7bit but it doesn't seem to make any difference. 我尝试将ASCII更改为UTF-7，因为Outlook以7位发送数据，但似乎没有任何区别。
Due to the HTML in the email I'm receiving, when I pass the email in, the formatting is wrong and sometimes I'll just get garbage in the email. 由于我收到的电子邮件中的HTML，当我传递电子邮件时，格式错误，有时我会在电子邮件中得到垃圾。
Update 更新
Full email headers as requested 根据要求提供完整的电子邮件标题
Message-ID: <000d01d0dc52$0c0d4690$2427d3b0$@chrisboard.co.uk>
MIME-Version: 1.0
Content-Type: multipart/alternative;
boundary="----=_NextPart_000_000E_01D0DC5A.6DD24AD0"
X-Mailer: Microsoft Outlook 15.0
Thread-Index: AdDcUeHbbPyOUTipQ462DEYroR+DWg==
Content-Language: en-gb
This is a multipart message in MIME format.
------=_NextPart_000_000E_01D0DC5A.6DD24AD0
Content-Type: text/plain;
charset="us-ascii"
Content-Transfer-Encoding: 7bit
This is the content of the message
------=_NextPart_000_000E_01D0DC5A.6DD24AD0
Content-Type: text/html;
charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
<html xmlns:v=3D"urn:schemas-microsoft-com:vml" =
xmlns:o=3D"urn:schemas-microsoft-com:office:office" =
xmlns:w=3D"urn:schemas-microsoft-com:office:word" =
xmlns:m=3D"http://schemas.microsoft.com/office/2004/12/omml" =
xmlns=3D"http://www.w3.o
1 个解决方案
解决方案1
1 已采纳 2015-08-24 10:06:26
Quoted-printable and ASCII text with long lines and = 带引号的可打印和ASCII文本，带有长行和=
The html attachment is encoded using quoted-printable encoding . html附件使用quoted-printable encoding编码 。 Quoted-printable uses special 3 bytes sequences starting with = . Quoted-printable使用以=开头的特殊3字节序列。 Quoted printable encodes = as =3D . 引用的可打印编码= =3D 。 It is the only printable ascii character (33-126) that must be encoded. 它是唯一必须编码的可打印ASCII字符（33-126）。
BTW = at end of line is also product of quoted-printable encoding. BTW =行尾也是带quoted-printable编码的乘积。 It "breaks" long lines. 它“折断”了长行。
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