带有非ASCII长名称的电子邮件附件 [英] Email attachment with long non-ascii name
问题描述
我尝试发送 System.Net.Mail.MailMessage 和 System.Net.Mail.Attachment 。
附件名称为Счёт-договор№4321от4июля.pdf
Name of attachment is "Счёт-договор №4321 от 4 июля.pdf"
附件创建代码：
var nameEncoding = Encoding.UTF8;
return new System.Net.Mail.Attachment(new MemoryStream(bytes),
MessageBodiesHelpers.EncodeAttachmentName(fileName, nameEncoding),
attachment.MediaType)
{
TransferEncoding = TransferEncoding.Base64,
NameEncoding = nameEncoding
};
MessageBodiesHelpers.EncodeAttachmentName 中的代码取自< a href = https://social.msdn.microsoft.com/Forums/en-US/b6c764f7-4697-4394-b45f-128a24306d55/40-smtpclientsend-attachments-mit-umlauten-im-dateinamen?forum=dotnetframeworkde > https://social.msdn.microsoft.com/Forums/zh-CN/b6c764f7-4697-4394-b45f-128a24306d55/40-smtpclientsend-attachments-mit-umlauten-im-dateinamen?forum=dotnetframeworkde
如果我将该附件发送到gmail或ms exchange，则附件名称已成功解码。 但是！
If I send that attachment to gmail or ms exchange, then name of attachment decoded successfully. BUT!
如果我将该附件发送到 icloud ，那么我会收到 ????-??? ????№4321от4????。pdf
If I send that attachment to icloud then I get "????-??????? №4321 от4 ????.pdf"
邮件附件标题：
来自ms交换：
Content-Type: application/pdf;
name="=?utf-8?B?0KHRh9GR0YIt0LTQ?==?utf-8?B?vtCz0L7QstC+0YAg?==?utf-8?B?4oSWNDMyMSDQvtGC?==?utf-8?B?IDQg0LjRjtC70Y8u?==?utf-8?B?cGRm?="
Content-Transfer-Encoding: base64
Content-Disposition: attachment
来自icloud：
Content-Transfer-Encoding: BASE64
Content-Type: APPLICATION/PDF;
name="????-??????? =?utf-8?B?4oSWNDMyMSDQvtGC?= 4 ????.pdf"
如何格式化icloud的名称？
How to format name for icloud?
upd
如果我将邮件从Outlook（MS交换）转发到icloud，则附件名称成功解码。标头：
If I forward message from outlook (ms exchange) to icloud, then name of attachment decoded successfully. Headers:
Content-Transfer-Encoding: BASE64
Content-Disposition: ATTACHMENT;
size=200702;
modification-date="Mon, 04 Jul 2016 13:40:22 GMT";
filename*=utf-8''%D0%A1%D1%87%D1%91%D1%82%2D%D0%B4%D0%BE%D0%B3%D0%BE%D0%B2%D0%BE%D1%80%20%E2%84%964321%20%D0%BE%D1%82%204%20%D0%B8%D1%8E%D0%BB%D1%8F.pdf;
creation-date="Mon, 04 Jul 2016 13:40:22 GMT"
Content-Type: APPLICATION/PDF;
name*=utf-8''%D0%A1%D1%87%D1%91%D1%82%2D%D0%B4%D0%BE%D0%B3%D0%BE%D0%B2%D0%BE%D1%80%20%E2%84%964321%20%D0%BE%D1%82%204%20%D0%B8%D1%8E%D0%BB%D1%8F.pdf
upd2
如果我使用icloud（icloud.com）的Web界面阅读邮件，则附件的名称已成功解码。
If I read messages using web interface of icloud (icloud.com), then name of attachment decoded successfully.
推荐答案
在.NET中4.0 SmtpClient现在实现RFC行长度限制（76个字符）。这需要对编码过程进行广泛的更改，而不会涉及您所描述的问题。
In .NET 4.0 SmtpClient now implements the RFC line length limits (76 chars). This required extensive changes to the encoding process and not covered a few issues like the one you describe.
在您的情况下，存在非ASCII附件名称的问题，将被编码为超过41个utf-8字节（Encoding.UTF8.GetByteCount（fileName）;）。在这种情况下，名称被编码两次，并且其中可能会有额外的换行符。唯一已知的解决方法是限制非ascii文件名的长度。
In your case, there is an issue with non-ascii attachment names that would be encoded to more than 41 utf-8 bytes (Encoding.UTF8.GetByteCount(fileName);). In this scenario the names are encoded twice and may have extra line breaks in them. The only known workaround is to limit the length of non-ascii file names.
您可以阅读此发布有关您的问题的更多信息
you can read this post for more info about your issue
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