尝试将 eml 文件作为附件插入时出现错误 "The input is not a valid Base-64 string as it contains a non-base 64 character"

Question

我在 c# 中有一个 MailMessage，我想将其转换为 EML 以作为附件插入到另一个系统中，但我得到的错误是

输入的 Base-64 字符串无效，因为它包含非 Base-64 字符、两个以上的填充字符或填充字符中的非法字符

没有使用textBody..我只是传入html

public Task<string> CreateEml(string @from, string to, string subject, string htmlBody, string textBody, List<Attachment> attachments = null)
    {
        using (var message = new MailMessage())
        {               
            message.To.Add(new MailAddress(to));
            message.From = new MailAddress(@from);
            //message.Bcc.Add(new MailAddress(bcc));
            message.Subject = subject;
            message.Body = htmlBody;
            message.IsBodyHtml = true;
            message.BodyEncoding = System.Text.Encoding.UTF8;
            if (attachments != null)
            {
                foreach (var item in attachments)
                {
                    message.Attachments.Add(item);
                }
            }

            if (!string.IsNullOrEmpty(textBody))
            {
                using (var stream = new MemoryStream())
                using (var writer = new StreamWriter(stream))
                {
                    writer.Write(textBody);
                    message.AlternateViews.Add(new AlternateView(stream));
                    var eml = message.ToEml();
                    return Task.FromResult(eml);
                }
            }

            return Task.FromResult(message.ToEml());
        }
    }

有一个扩展方法 ToEml() 可以执行此操作

 public static string ToEml(this MailMessage message)
    {
        var assembly = typeof(SmtpClient).Assembly;
        var mailWriterType = assembly.GetType("System.Net.Mail.MailWriter");

        using (var memoryStream = new MemoryStream())
        {
            // Get reflection info for MailWriter contructor
            var mailWriterContructor = mailWriterType.GetConstructor(BindingFlags.Instance | BindingFlags.NonPublic, null, new[] { typeof(Stream) }, null);

            // Construct MailWriter object with our FileStream
            var mailWriter = mailWriterContructor.Invoke(new object[] { memoryStream });

            // Get reflection info for Send() method on MailMessage
            var sendMethod = typeof(MailMessage).GetMethod("Send", BindingFlags.Instance | BindingFlags.NonPublic);

            // Call method passing in MailWriter
            sendMethod.Invoke(message, BindingFlags.Instance | BindingFlags.NonPublic, null, new[] { mailWriter, true, true }, null);

            // Finally get reflection info for Close() method on our MailWriter
            var closeMethod = mailWriter.GetType().GetMethod("Close", BindingFlags.Instance | BindingFlags.NonPublic);

            // Call close method
            closeMethod.Invoke(mailWriter, BindingFlags.Instance | BindingFlags.NonPublic, null, new object[] { }, null);

            return Encoding.ASCII.GetString(memoryStream.ToArray());
        }
    }

此结果数据被分配给 data.EmailDataBus 并用于将电子邮件作为附件插入到第三方系统，如下所示

attachment.FileInfo[0] = new FileInfoClass
            {
                Description = emailDescription,
                Category = "EMAIL",
                FileName = "NewBusiness.eml",
                Data = data.EmailDataBus,
            };

            using (var webService = new ConneXion())
            {
                webService.Url = CloudConfigurationManager.GetSetting("tam.webservice.url");

                var response = webService.InsertAttachment(ref attachment);

我得到的错误信息是

输入的 Base-64 字符串无效，因为它包含非 Base-64 字符、两个以上的填充字符或填充字符中的非法字符

data.EmailBus 中的数据如下所示，注意我没有包括所有 base64，但页眉和页脚完好无损

https://plnkr.co/edit/n71EFK2gHRj6Nn4HX1Sn?p=preview

Answer 1

原来我只需要将整个东西编码为 base64.. 这有点奇怪，因为部分数据已经是 base64.. 但我想不是全部。无论如何，现在一切正常:)附件连接正常。

byte[] emaildata = Encoding.UTF8.GetBytes(data.EmailDataBus);
 string b64 = Convert.ToBase64String(emaildata);

尝试将 eml 文件作为附件插入时出现错误 "The input is not a valid Base-64 string as it contains a non-base 64 character"

Trying to insert eml file as attachment gives error "The input is not a valid Base-64 string as it contains a non-base 64 character"

c#

email

base64

eml