/// <summary>
/// Sends the specified message to an SMTP server for delivery.
/// </summary>
/// <param name="message">An OpaqueMail.MailMessage that contains the message to send.</param>
public async Task SendAsync(MailMessage message)
{
// If the message isn't encoded, do so now.
if (string.IsNullOrEmpty(message.RawBody))
{
message.Prepare();
}
// Perform requested S/MIME signing and/or encryption.
message.SmimePrepare(this);
string rawBody = message.RawBody;
// Connect to the SMTP server.
TcpClient SmtpTcpClient = new TcpClient();
SmtpTcpClient.Connect(Host, Port);
Stream SmtpStream = SmtpTcpClient.GetStream();
// Use stream readers and writers to simplify I/O.
StreamReader reader = new StreamReader(SmtpStream);
StreamWriter writer = new StreamWriter(SmtpStream);
writer.AutoFlush = true;
// Read the welcome message.
string response = await reader.ReadLineAsync();
// Send EHLO and find out server capabilities.
await writer.WriteLineAsync("EHLO " + Host);
char[] charBuffer = new char[Constants.SMALLBUFFERSIZE];
int bytesRead = await reader.ReadAsync(charBuffer, 0, Constants.SMALLBUFFERSIZE);
response = new string(charBuffer, 0, bytesRead);
if (!response.StartsWith("2"))
{
throw new SmtpException("Unable to connect to remote server '" + Host + "'. Sent 'EHLO' and received '" + response + "'.");
}
// Stand up a TLS/SSL stream.
if (EnableSsl)
{
await writer.WriteLineAsync("STARTTLS");
response = await reader.ReadLineAsync();
if (!response.StartsWith("2"))
{
throw new SmtpException("Unable to start TLS/SSL protection with '" + Host + "'. Received '" + response + "'.");
}
SmtpStream = new SslStream(SmtpStream);
((SslStream)SmtpStream).AuthenticateAsClient(Host, null, SslProtocols, true);
reader = new StreamReader(SmtpStream);
writer = new StreamWriter(SmtpStream);
writer.AutoFlush = true;
await writer.WriteLineAsync("EHLO " + Host);
bytesRead = await reader.ReadAsync(charBuffer, 0, Constants.SMALLBUFFERSIZE);
response = new string(charBuffer, 0, bytesRead);
}
// Authenticate using the AUTH LOGIN command.
if (Credentials != null)
{
NetworkCredential cred = (NetworkCredential)Credentials;
await writer.WriteLineAsync("AUTH LOGIN");
response = await reader.ReadLineAsync();
if (!response.StartsWith("3"))
{
throw new SmtpException("Unable to authenticate with server '" + Host + "'. Received '" + response + "'.");
}
await writer.WriteLineAsync(Functions.ToBase64String(cred.UserName));
response = await reader.ReadLineAsync();
await writer.WriteLineAsync(Functions.ToBase64String(cred.Password));
response = await reader.ReadLineAsync();
if (!response.StartsWith("2"))
{
throw new SmtpException("Unable to authenticate with server '" + Host + "'. Received '" + response + "'.");
}
}
// Build our raw headers block.
StringBuilder rawHeaders = new StringBuilder(Constants.SMALLSBSIZE);
// Specify who the message is from.
rawHeaders.Append(Functions.SpanHeaderLines("From: " + Functions.EncodeMailHeader(Functions.ToMailAddressString(message.From))) + "\r\n");
await writer.WriteLineAsync("MAIL FROM:<" + message.From.Address + ">");
response = await reader.ReadLineAsync();
if (!response.StartsWith("2"))
{
throw new SmtpException("Exception communicating with server '" + Host + "'. Sent 'MAIL FROM' and received '" + response + "'.");
}
// Identify all recipients of the message.
if (message.To.Count > 0)
{
rawHeaders.Append(Functions.SpanHeaderLines("To: " + Functions.EncodeMailHeader(message.To.ToString())) + "\r\n");
}
foreach (MailAddress address in message.To)
{
await writer.WriteLineAsync("RCPT TO:<" + address.Address + ">");
response = await reader.ReadLineAsync();
if (!response.StartsWith("2"))
{
throw new SmtpException("Exception communicating with server '" + Host + "'. Sent 'RCPT TO' and received '" + response + "'.");
}
}
if (message.CC.Count > 0)
{
rawHeaders.Append(Functions.SpanHeaderLines("CC: " + Functions.EncodeMailHeader(message.CC.ToString())) + "\r\n");
}
foreach (MailAddress address in message.CC)
{
await writer.WriteLineAsync("RCPT TO:<" + address.Address + ">");
response = await reader.ReadLineAsync();
if (!response.StartsWith("2"))
{
throw new SmtpException("Exception communicating with server '" + Host + "'. Sent 'RCPT TO' and received '" + response + "'.");
}
}
foreach (MailAddress address in message.Bcc)
{
await writer.WriteLineAsync("RCPT TO:<" + address.Address + ">");
response = await reader.ReadLineAsync();
if (!response.StartsWith("2"))
{
throw new SmtpException("Exception communicating with server '" + Host + "'. Sent 'RCPT TO' and received '" + response + "'.");
}
}
// Ensure a content type is set.
if (string.IsNullOrEmpty(message.ContentType))
{
if (Functions.AppearsHTML(message.Body))
{
message.ContentType = "text/html";
}
else
{
message.ContentType = "text/plain";
}
}
message.Headers["Content-Type"] = message.ContentType + (!string.IsNullOrEmpty(message.CharSet) ? "; charset=\"" + message.CharSet + "\"" : "");
// If the body hasn't been processed, handle encoding of extended characters.
if (string.IsNullOrEmpty(rawBody) && !string.IsNullOrEmpty(message.Body))
{
bool extendedCharacterFound = false;
foreach (char headerCharacter in message.Body.ToCharArray())
{
if (headerCharacter > 127)
{
extendedCharacterFound = true;
break;
}
}
if (extendedCharacterFound)
{
message.ContentTransferEncoding = "base64";
message.Body = Functions.ToBase64String(message.Body);
}
rawBody = message.Body;
}
if (!string.IsNullOrEmpty(message.ContentTransferEncoding))
{
message.Headers["Content-Transfer-Encoding"] = message.ContentTransferEncoding;
}
// Send the raw message.
await writer.WriteLineAsync("DATA");
response = await reader.ReadLineAsync();
if (!response.StartsWith("3"))
{
throw new SmtpException("Exception communicating with server '" + Host + "'. Sent 'DATA' and received '" + response + "'.");
}
rawHeaders.Append(Functions.SpanHeaderLines("Subject: " + Functions.EncodeMailHeader(message.Subject, 32)) + "\r\n");
foreach (string rawHeader in message.Headers)
{
switch (rawHeader.ToUpper())
{
case "BCC":
case "CC":
case "FROM":
case "SUBJECT":
case "TO":
break;
default:
rawHeaders.Append(Functions.SpanHeaderLines(rawHeader + ": " + message.Headers[rawHeader]) + "\r\n");
break;
}
}
await writer.WriteAsync(rawHeaders.ToString() + "\r\n" + rawBody + "\r\n.\r\n");
response = await reader.ReadLineAsync();
if (!response.StartsWith("2"))
{
throw new SmtpException("Exception communicating with server '" + Host + "'. Sent message and received '" + response + "'.");
}
// Clean up this connection.
await writer.WriteLineAsync("QUIT");
writer.Dispose();
reader.Dispose();
SmtpStream.Dispose();
SmtpTcpClient.Close();
}
/// <summary>
/// Sends the specified message to an SMTP server for delivery without making modifications to the body.
/// Necessary because the standard SmtpClient.Send() may slightly alter messages, invalidating signatures.
/// </summary>
/// <param name="message">An OpaqueMail.MailMessage that contains the message to send.</param>
private async Task SmimeSendRawAsync(MailMessage message)
{
// Connect to the SMTP server.
TcpClient SmtpTcpClient = new TcpClient();
SmtpTcpClient.Connect(Host, Port);
Stream SmtpStream = SmtpTcpClient.GetStream();
// Use stream readers and writers to simplify I/O.
StreamReader reader = new StreamReader(SmtpStream);
StreamWriter writer = new StreamWriter(SmtpStream);
writer.AutoFlush = true;
// Read the welcome message.
string response = await reader.ReadLineAsync();
// Send EHLO and find out server capabilities.
await writer.WriteLineAsync("EHLO " + Host);
char[] charBuffer = new char[Constants.SMALLBUFFERSIZE];
int bytesRead = await reader.ReadAsync(charBuffer, 0, Constants.SMALLBUFFERSIZE);
response = new string(charBuffer, 0, bytesRead);
if (!response.StartsWith("2"))
{
throw new SmtpException("Unable to connect to remote server '" + Host + "'. Sent 'EHLO' and received '" + response + "'.");
}
// Stand up a TLS/SSL stream.
if (EnableSsl)
{
await writer.WriteLineAsync("STARTTLS");
response = await reader.ReadLineAsync();
if (!response.StartsWith("2"))
{
throw new SmtpException("Unable to start TLS/SSL protection with '" + Host + "'. Received '" + response + "'.");
}
SmtpStream = new SslStream(SmtpStream);
((SslStream)SmtpStream).AuthenticateAsClient(Host);
reader = new StreamReader(SmtpStream);
writer = new StreamWriter(SmtpStream);
writer.AutoFlush = true;
}
// Authenticate using the AUTH LOGIN command.
if (Credentials != null)
{
NetworkCredential cred = (NetworkCredential)Credentials;
await writer.WriteLineAsync("AUTH LOGIN");
response = await reader.ReadLineAsync();
if (!response.StartsWith("3"))
{
throw new SmtpException("Unable to authenticate with server '" + Host + "'. Received '" + response + "'.");
}
await writer.WriteLineAsync(Functions.ToBase64String(cred.UserName));
response = await reader.ReadLineAsync();
await writer.WriteLineAsync(Functions.ToBase64String(cred.Password));
response = await reader.ReadLineAsync();
if (!response.StartsWith("2"))
{
throw new SmtpException("Unable to authenticate with server '" + Host + "'. Received '" + response + "'.");
}
}
// Build our raw headers block.
StringBuilder rawHeaders = new StringBuilder(Constants.SMALLSBSIZE);
// Specify who the message is from.
rawHeaders.Append(Functions.SpanHeaderLines("From: " + Functions.EncodeMailHeader(Functions.ToMailAddressString(message.From))) + "\r\n");
await writer.WriteLineAsync("MAIL FROM:<" + message.From.Address + ">");
response = await reader.ReadLineAsync();
if (!response.StartsWith("2"))
{
throw new SmtpException("Exception communicating with server '" + Host + "'. Sent 'MAIL FROM' and received '" + response + "'.");
}
// Identify all recipients of the message.
if (message.To.Count > 0)
{
rawHeaders.Append(Functions.SpanHeaderLines("To: " + Functions.EncodeMailHeader(Functions.ToMailAddressString(message.To))) + "\r\n");
}
foreach (MailAddress address in message.To)
{
await writer.WriteLineAsync("RCPT TO:<" + address.Address + ">");
response = await reader.ReadLineAsync();
if (!response.StartsWith("2"))
{
throw new SmtpException("Exception communicating with server '" + Host + "'. Sent 'RCPT TO' and received '" + response + "'.");
}
}
if (message.CC.Count > 0)
{
rawHeaders.Append(Functions.SpanHeaderLines("CC: " + Functions.EncodeMailHeader(Functions.ToMailAddressString(message.CC))) + "\r\n");
}
foreach (MailAddress address in message.CC)
{
await writer.WriteLineAsync("RCPT TO:<" + address.Address + ">");
response = await reader.ReadLineAsync();
if (!response.StartsWith("2"))
{
throw new SmtpException("Exception communicating with server '" + Host + "'. Sent 'RCPT TO' and received '" + response + "'.");
}
}
foreach (MailAddress address in message.Bcc)
{
await writer.WriteLineAsync("RCPT TO:<" + address.Address + ">");
response = await reader.ReadLineAsync();
if (!response.StartsWith("2"))
{
throw new SmtpException("Exception communicating with server '" + Host + "'. Sent 'RCPT TO' and received '" + response + "'.");
}
}
// Send the raw message.
await writer.WriteLineAsync("DATA");
response = await reader.ReadLineAsync();
if (!response.StartsWith("3"))
{
throw new SmtpException("Exception communicating with server '" + Host + "'. Sent 'DATA' and received '" + response + "'.");
}
// If a read-only mail message is passed in with its raw headers and body, save a few steps by sending that directly.
if (message is ReadOnlyMailMessage)
{
await writer.WriteAsync(((ReadOnlyMailMessage)message).RawHeaders + "\r\n" + ((ReadOnlyMailMessage)message).RawBody + "\r\n.\r\n");
}
else
{
rawHeaders.Append(Functions.SpanHeaderLines("Subject: " + Functions.EncodeMailHeader(message.Subject)) + "\r\n");
foreach (string rawHeader in message.Headers)
{
switch (rawHeader.ToUpper())
{
case "BCC":
case "CC":
case "FROM":
case "SUBJECT":
case "TO":
break;
default:
rawHeaders.Append(Functions.SpanHeaderLines(rawHeader + ": " + message.Headers[rawHeader]) + "\r\n");
break;
}
}
await writer.WriteAsync(rawHeaders.ToString() + "\r\n" + message.Body + "\r\n.\r\n");
}
response = await reader.ReadLineAsync();
if (!response.StartsWith("2"))
{
throw new SmtpException("Exception communicating with server '" + Host + "'. Sent message and received '" + response + "'.");
}
// Clean up this connection.
await writer.WriteLineAsync("QUIT");
writer.Dispose();
reader.Dispose();
SmtpStream.Dispose();
SmtpTcpClient.Close();
}