c# MailMessage 自定义 header - 使用 System.Net.Mail；

Question

这是我测试 MailMessage header 的方法:

   private void Send_Email(string smtp_server, int port, string display_name, string from, string to, string subject, string html_body, string sender_email, string sender_password)
        {
            MailMessage mail = new MailMessage();
            mail.From = new MailAddress(from, display_name, Encoding.UTF8);
            mail.To.Add(to);

            mail.SubjectEncoding = Encoding.UTF8;
            mail.Subject = subject;

            mail.Headers.Add("Reply-To", "Reply-To__ <" + from + ">");
            mail.Headers.Add("Sender", from);
            mail.Headers.Add("Return-Path", from);
            mail.Headers.Add("MIME-Version", "1.0");

            string boundary = Guid.NewGuid().ToString();
            mail.Headers.Add("Content-Type", "multipart/mixed; boundary=--" + boundary);

            //mail.Headers.Add("", Environment.NewLine);
            //mail.Headers.Add("", Environment.NewLine);

            //mail.Headers.Add("", "--" + boundary);
            //mail.Headers.Add("Content-Type", "text/html; charset=utf-8");
            //mail.Headers.Add("Content-Transfer-Encoding", "base64");
            //mail.Headers.Add("", Environment.NewLine);
            //var bytes = Encoding.UTF8.GetBytes(html_body);
            //var base64 = Convert.ToBase64String(bytes);
            //mail.Headers.Add("", base64.ToString());
            //mail.Headers.Add("", "--" + boundary);

            SmtpClient smtp = new SmtpClient();
            smtp.UseDefaultCredentials = true;
            //smtp.Credentials = new System.Net.NetworkCredential(sender_email, sender_password);
            smtp.Host = smtp_server;
            smtp.Port = port;
            smtp.Timeout = 60000;

            smtp.SendCompleted += (s, e) =>
            {
                if (e.Cancelled)
                {
                    MessageBox.Show("sending email was canceled");
                }
                if (e.Error != null)
                {
                    MessageBox.Show("sending email was failed -> Error : " + e.Error.ToString());
                }
                else
                {
                    MessageBox.Show("email was sent successfully");
                }

                mail.Dispose();
            };

            try
            {
                smtp.SendAsync(mail, null);
            }
            catch (System.Net.Mail.SmtpException exp)
            {
                MessageBox.Show("sending email was failed, SmtpException -> Error : " + exp.ToString());

                mail.Dispose();
            }
        }

在 php 中你的双手是自由的，可以很好地制作标题和邮件结构，
看看这个例子:
http://www.sanwebe.com/2011/01/send-php-mail-with-attachment
我想在 .Net 中做类似 php 的事情，并使用标题制作我的邮件结构。
但是我的代码中的错误与这些行有关:

mail.Headers.Add("", "blo blo blo");

和错误:

The name part can not be empty...

我如何绕过该错误并使用标题创建我的邮件的每一个和平:
比如 -> Body - Attachments - 等

---

回答完我的问题后，我会弄清楚如何组合多个 Content-Types :
例如 -> html - plain/text - octet - 等等

Answer 1

我认为这属于 RFC 2822，https://www.rfc-editor.org/rfc/rfc2822#section-2.2 :

2.2. Header Fields

Header fields are lines composed of a field name, followed by acolon (":"), followed by a field body, and terminated by CRLF. Afield name MUST be composed of printable US-ASCII characters (i.e.,characters that have values between 33 and 126, inclusive), except
colon. A field body may be composed of any US-ASCII characters,
except for CR and LF. However, a field body may contain CRLF when
used in header "folding" and "unfolding" as described in section2.2.3. All field bodies MUST conform to the syntax described in sections 3 and 4 of this standard.

似乎不允许空字符串。

使用 5 小时的 SMTP 超时时间过长。 5 秒到 60 秒的范围更合理。