/// <summary>
/// Attempts to find and process the reason an email bounced by digging through all body parts.
/// </summary>
/// <param name="bodyParts">Array of BodyParts to dig through; may include child body parts.</param>
/// <param name="bouncePair">out. A BouncePair object containing details of the bounce (if a reason was found).</param>
/// <param name="bounceMessage">out. The text to use as the reason found why the bounce occurred.</param>
/// <returns>true if a reason was found, else false.</returns>
internal bool FindBounceReason(BodyPart[] bodyParts, out BouncePair bouncePair, out string bounceMessage, out EmailProcessingDetails bounceIdentification)
{
foreach (BodyPart b in bodyParts)
{
if (b.ContentType.MediaType.StartsWith("multipart/", StringComparison.OrdinalIgnoreCase))
{
// Just a container for other body parts so check them.
if (FindBounceReason(b.BodyParts, out bouncePair, out bounceMessage, out bounceIdentification))
{
return(true);
}
}
else if (b.ContentType.MediaType.Equals("text/plain", StringComparison.OrdinalIgnoreCase))
{
// Only useful to examine text/plain body parts (so not "image/gif" etc).
if (ParseBounceMessage(b.GetDecodedBody(), out bouncePair, out bounceMessage, out bounceIdentification))
{
return(true);
}
}
// else
// Console.WriteLine("\tSkipped bodypart \"" + b.ContentType.MediaType + "\".");
}
// Still here so haven't found anything useful.
bouncePair.BounceCode = MantaBounceCode.Unknown;
bouncePair.BounceType = MantaBounceType.Unknown;
bounceMessage = string.Empty;
bounceIdentification = new EmailProcessingDetails();
bounceIdentification.BounceIdentifier = BounceIdentifier.NotIdentifiedAsABounce;
return(false);
}
/// <summary>
/// Examines an SMTP response that is thought to relate to delivery of an email failing.
/// </summary>
/// <param name="message">An SMTP response either found as the "Diagnostic-Code" value in a Non-Delivery Report
/// or received directly from another MTA in an SMTP session.</param>
/// <param name="bouncePair">out. Details of the Bounce (or not) based on details found in <paramref name="message"/>.</param>
/// <param name="bounceMessage">out. The message found that indicated a Bounce or string.Empty if it wasn't
/// found to indicate a bounce.</param>
/// <returns>true if a bounce was positively identified, else false.</returns>
internal bool ParseSmtpDiagnosticCode(string message, out BouncePair bouncePair, out string bounceMessage, out EmailProcessingDetails bounceIdentification)
{
// Remove "smtp;[possible whitespace]" if it appears at the beginning of the message.
if (message.StartsWith("smtp;", StringComparison.OrdinalIgnoreCase))
{
message = message.Substring("smtp;".Length).Trim();
}
if (ParseBounceMessage(message, out bouncePair, out bounceMessage, out bounceIdentification))
{
return(true);
}
bounceIdentification.BounceIdentifier = BounceIdentifier.NotIdentifiedAsABounce;
return(false);
}
/// <summary>
/// Converts an SMTP status code into a MantaBounceType and MantaBounceCode pairing.
/// </summary>
/// <param name="smtpCode">A standard SMTP code, e.g. "550".</param>
/// <returns>The appropriate MantaBounceCode for the SMTP code provided in <paramref name="smtpCode"/>.</returns>
internal BouncePair ConvertSmtpCodeToMantaBouncePair(int smtpCode)
{
BouncePair bp = new BouncePair();
// Based on the first character of the SMTP code, we can tell if it's not actually a bounce
// or at least get the BounceType (whether it's a permanent or temporary problem).
char codeClass = smtpCode.ToString()[0];
if (codeClass == '2' || codeClass == '3')
{
// All done - not a bounce.
bp.BounceType = MantaBounceType.Unknown;
bp.BounceCode = MantaBounceCode.NotABounce;
return(bp);
}
else if (codeClass == '4')
{
// Temporary problem.
bp.BounceType = MantaBounceType.Soft;
}
else if (codeClass == '5')
{
// Permanent problem.
bp.BounceType = MantaBounceType.Hard;
}
else
{
// Perhaps not a valid SMTP code at all.
bp.BounceType = MantaBounceType.Unknown;
bp.BounceCode = MantaBounceCode.Unknown;
return(bp);
}
switch (smtpCode)
{
case 200: // (nonstandard success response, see rfc876)
case 211: // System status, or system help reply
case 214: // Help message
case 220: // SMTP Service ready.
case 221: // Service closing transmission channel
case 250: // Requested mail action okay, completed
case 251: // The recipient is not local to the server, but the server will accept and forward the message.
case 252: // The recipient cannot be VRFYed, but the server accepts the message and attempts delivery.
case 354: // Start mail input; end with <CRLF>.<CRLF>
bp.BounceType = MantaBounceType.Unknown;
bp.BounceCode = MantaBounceCode.NotABounce;
return(bp);
case 420: // Timeout communication problem encountered during transmission
case 421: // Service not available, closing transmission channel
case 521: // <domain> does not accept mail (see rfc1846)
case 530: // Access denied (???a Sendmailism)
bp.BounceCode = MantaBounceCode.ServiceUnavailable;
break;
case 431: // Receiving mail server's disk is full
case 452: // Requested action not taken: insufficient system storage
case 552: // Requested mail action aborted: exceeded storage allocation
bp.BounceCode = MantaBounceCode.MailboxFull;
break;
case 450: // Requested mail action not taken: mailbox unavailable
case 550: // Requested action not taken: mailbox unavailable
case 551: // User not local; please try <forward-path>
case 553: // Requested action not taken: mailbox name not allowed
bp.BounceCode = MantaBounceCode.BadEmailAddress;
break;
case 571: // Message refused.
bp.BounceCode = MantaBounceCode.RelayDenied;
break;
case 451: // Requested action aborted: local error in processing
case 500: // Syntax error, command unrecognised
case 501: // Syntax error in parameters or arguments
case 502: // Command not implemented
case 503: // Bad sequence of commands
case 504: // Command parameter not implemented
case 554: // Transaction failed
bp.BounceCode = MantaBounceCode.General;
break;
default:
bp.BounceCode = MantaBounceCode.Unknown;
break;
}
return(bp);
}
/// <summary>
/// Converts a Non-Delivery Report (NDR) code to a MantaBounceType and MantaBounceCode.
/// </summary>
/// <param name="smtpCode">An NDR code, e.g. "4.4.7". See here for more:
/// http://tools.ietf.org/html/rfc3463.</param>
/// <returns>A BouncePair object with the appropriate MantaBounceCode and MantaBounceType values
/// for the NDR code provided in <paramref name="ndrCode"/>.</returns>
internal BouncePair ConvertNdrCodeToMantaBouncePair(string ndrCode)
{
BouncePair bp = new BouncePair();
int firstDotPos = ndrCode.IndexOf('.');
// If it ain't got no dots, it ain't a proper NDR code.
if (firstDotPos == -1)
{
bp.BounceType = MantaBounceType.Unknown;
bp.BounceCode = MantaBounceCode.Unknown;
return(bp);
}
// Identify if it's a temporary or permanent bounce (or even not one at all).
if (ndrCode.StartsWith("2") || ndrCode.StartsWith("3"))
{
// All done - not a bounce.
bp.BounceType = MantaBounceType.Unknown;
bp.BounceCode = MantaBounceCode.NotABounce;
return(bp);
}
if (ndrCode.StartsWith("4."))
{
bp.BounceType = MantaBounceType.Soft;
}
else if (ndrCode.StartsWith("5."))
{
bp.BounceType = MantaBounceType.Hard;
}
else
{
bp.BounceType = MantaBounceType.Unknown;
bp.BounceCode = MantaBounceCode.Unknown;
return(bp);
}
// Check the rest of the code.
string endPart = ndrCode.Substring(firstDotPos);
// List of status codes as per RFC 3463 ().
//
// TODO BenC (2013-07-08): Needs refining/reviewing as just did a rough first pass through.
switch (endPart)
{
case ".0.0": // "Other undefined Status". Should be used for all errors for which only the class of the error is known.
bp.BounceCode = MantaBounceCode.BounceUnknown;
break;
case ".1.5": // Destination mailbox address valid
bp.BounceCode = MantaBounceCode.NotABounce;
break;
case ".1.0": // Other address status
case ".1.1": // Bad destination mailbox address
case ".1.2": // Bad destination system address
case ".1.3": // Bad destination mailbox address syntax
case ".1.4": // Destination mailbox address ambiguous
case ".1.6": // Mailbox has moved
case ".2.0": // Other or undefined mailbox status
case ".2.1": // Mailbox disabled, not accepting messages
bp.BounceCode = MantaBounceCode.BadEmailAddress;
break;
case ".2.2": // Mailbox full
case ".3.1": // Mail system full
bp.BounceCode = MantaBounceCode.MailboxFull;
break;
case ".2.3": // Message length exceeds administrative limit.
case ".3.4": // Message too big for system
bp.BounceCode = MantaBounceCode.MessageSizeTooLarge;
break;
case ".2.4": // Mailing list expansion problem
case ".3.0": // Other or undefined mail system status
case ".3.2": // System not accepting network messages
case ".3.3": // System not capable of selected features
case ".4.0": // Other or undefined network or routing status
case ".4.1": // No answer from host
case ".4.2": // Bad connection
case ".4.3": // Routing server failure
case ".4.4": // Unable to route
case ".4.5": // Network congestion
case ".4.6": // Routing loop detected
case ".4.7": // Delivery time expired
case ".5.0": // Other or undefined protocol status
bp.BounceCode = MantaBounceCode.UnableToConnect;
break;
case ".1.7": // Bad sender's mailbox address syntax
case ".1.8": // Bad sender's system address
bp.BounceCode = MantaBounceCode.ConfigurationErrorWithSendingAddress;
break;
// BenC (2013-08-21): Don't know why these are commented out (doesn't affect things as they're handled by default anyway), but leaving for now.
/*
* case ".5.1": // Invalid command
* case ".5.2": // Syntax error
* case ".5.3": // Too many recipients
* case ".5.4": // Invalid command arguments
* case ".5.5": // Wrong protocol version
* case ".6.0": // Other or undefined media error
* case ".6.1": // Media not supported
* case ".6.2": // Conversion required and prohibited
* case ".6.3": // Conversion required but not supported
* case ".6.4": // Conversion with loss performed
* case ".6.5": // Conversion failed
* case ".7.0": // Other or undefined security status
* case ".7.1": // Delivery not authorized, message refused
* case ".7.2": // Mailing list expansion prohibited
* case ".7.3": // Security conversion required but not possible
* case ".7.4": // Security features not supported
* case ".7.5": // Cryptographic failure
* case ".7.6": // Cryptographic algorithm not supported
* case ".7.7": // Message integrity failure
*/
default:
// Do additional processing if no matches above.
bp.BounceCode = MantaBounceCode.General;
break;
}
return(bp);
}
/// <summary>
/// Attempts to find the reason for the bounce by running Bounce Rules, then checking for Non-Delivery Report codes,
/// and finally checking for SMTP codes.
/// </summary>
/// <param name="message">Could either be an email body part or a single or multiple line response from another MTA.</param>
/// <param name="bouncePair">out.</param>
/// <param name="bounceMessage">out.</param>
/// <returns>true if a positive match in <paramref name="message"/> was found indicating a bounce, else false.</returns>
internal bool ParseBounceMessage(string message, out BouncePair bouncePair, out string bounceMessage, out EmailProcessingDetails bounceIdentification)
{
bounceIdentification = new EmailProcessingDetails();
// Check all Bounce Rules for a match.
foreach (BounceRule r in BounceRulesManager.BounceRules)
{
// If we get a match, we're done processing Rules.
if (r.IsMatch(message, out bounceMessage))
{
bouncePair.BounceType = r.BounceTypeIndicated;
bouncePair.BounceCode = r.BounceCodeIndicated;
bounceMessage = message;
bounceIdentification.BounceIdentifier = BounceIdentifier.BounceRule;
bounceIdentification.MatchingBounceRuleID = r.RuleID;
bounceIdentification.MatchingValue = r.Criteria;
return(true);
}
}
// No Bounce Rules match the message so try to get a match on an NDR code ("5.1.1") or an SMTP code ("550").
// TODO: Handle several matches being found - somehow find The Best?
// Pattern: Should match like this:
// [anything at the beginning if present][then either an SMTP code or an NDR code, but both should be grabbed if
// they exist][then the rest of the content (if any)]
Match match = Regex.Match(message, RegexPatterns.SmtpResponse, RegexOptions.Singleline | RegexOptions.ExplicitCapture);
if (match.Success)
{
bounceMessage = match.Value;
// Check for anything useful with the NDR code first as it contains more specific detail than the SMTP code.
if (match.Groups["NdrCode"].Success && match.Groups["NdrCode"].Length > 0)
{
bouncePair = BounceRulesManager.Instance.ConvertNdrCodeToMantaBouncePair(match.Groups["NdrCode"].Value);
if (bouncePair.BounceType != MantaBounceType.Unknown)
{
bounceIdentification.BounceIdentifier = BounceIdentifier.NdrCode;
bounceIdentification.MatchingValue = match.Groups["NdrCode"].Value;
return(true);
}
}
// Try the SMTP code as there wasn't an NDR.
if (match.Groups["SmtpCode"].Success && match.Groups["SmtpCode"].Length > 0)
{
bouncePair = BounceRulesManager.Instance.ConvertSmtpCodeToMantaBouncePair(Int32.Parse(match.Groups["SmtpCode"].Value));
bounceIdentification.BounceIdentifier = BounceIdentifier.SmtpCode;
bounceIdentification.MatchingValue = match.Groups["SmtpCode"].Value;
return(true);
}
}
// Failed to identify a reason so shouldn't be a bounce.
bouncePair.BounceCode = MantaBounceCode.Unknown;
bouncePair.BounceType = MantaBounceType.Unknown;
bounceMessage = string.Empty;
bounceIdentification.BounceIdentifier = BounceIdentifier.NotIdentifiedAsABounce;
bounceIdentification.MatchingValue = string.Empty;
return(false);
}
/// <summary>
/// Examines an SMTP response message to identify detailed bounce information from it.
/// </summary>
/// <param name="response">The message that's come back from an external MTA when attempting to send an email.</param>
/// <param name="rcptTo">The email address that was being sent to.</param>
/// <param name="internalSendID">The internal Manta SendID.</param>
/// <returns>True if a bounce was found and recorded, false if not.</returns>
internal bool ProcessSmtpResponseMessage(string response, string rcptTo, int internalSendID, out EmailProcessingDetails bounceIdentification)
{
bounceIdentification = new EmailProcessingDetails();
// Check for TimedOutInQueue message first.
if (response.Equals(MtaParameters.TIMED_OUT_IN_QUEUE_MESSAGE, StringComparison.OrdinalIgnoreCase))
{
bounceIdentification = null;
MantaTimedOutInQueueEvent timeOut = new MantaTimedOutInQueueEvent
{
EventType = MantaEventType.TimedOutInQueue,
EmailAddress = rcptTo,
SendID = SendDB.GetSend(internalSendID).ID,
EventTime = DateTime.UtcNow
};
// Log to DB.
Save(timeOut);
// All done return true.
return(true);
}
BouncePair bouncePair = new BouncePair();
string bounceMessage = string.Empty;
if (ParseBounceMessage(response, out bouncePair, out bounceMessage, out bounceIdentification))
{
// Were able to find the bounce so create the bounce event.
MantaBounceEvent bounceEvent = new MantaBounceEvent
{
EventType = MantaEventType.Bounce,
EmailAddress = rcptTo,
BounceInfo = bouncePair,
SendID = SendDB.GetSend(internalSendID).ID,
// It is possible that the bounce was generated a while back, but we're assuming "now" for the moment.
// Might be good to get the DateTime found in the email at a later point.
EventTime = DateTime.UtcNow,
Message = response
};
// Log to DB.
Save(bounceEvent);
// All done return true.
return(true);
}
// Couldn't identify the bounce.
bounceIdentification.BounceIdentifier = BounceIdentifier.NotIdentifiedAsABounce;
return(false);
}
/// <summary>
/// Examines a non-delivery report for detailed bounce information.
/// </summary>
/// <param name="message"></param>
/// <param name="bounceType"></param>
/// <param name="bounceCode"></param>
/// <param name="bounceMessage"></param>
/// <returns></returns>
internal bool ParseNdr(string message, out BouncePair bouncePair, out string bounceMessage, out EmailProcessingDetails bounceIdentification)
{
bounceIdentification = new EmailProcessingDetails();
// Check for the Diagnostic-Code as hopefully contains more information about the error.
const string DiagnosticCodeFieldName = "Diagnostic-Code: ";
const string StatusFieldName = "Status: ";
StringBuilder diagnosticCode = new StringBuilder(string.Empty);
string status = string.Empty;
using (StringReader sr = new StringReader(message))
{
string line = sr.ReadToCrLf();
// While the string reader has stuff to read keep looping through each line.
while (!string.IsNullOrWhiteSpace(line) || sr.Peek() > -1)
{
if (line.StartsWith(DiagnosticCodeFieldName, StringComparison.OrdinalIgnoreCase))
{
// Found the diagnostic code.
// Remove the field name.
line = line.Substring(DiagnosticCodeFieldName.Length);
// Check to see if the disagnostic-code contains an SMTP response.
bool isSmtpResponse = line.StartsWith("smtp;", StringComparison.OrdinalIgnoreCase);
// Add the first line of the diagnostic-code.
diagnosticCode.AppendLine(line);
// Will be set to true when we find the next non diagnostic-code line.
bool foundNextLine = false;
// Loop to read multiline diagnostic-code.
while (!foundNextLine)
{
if (sr.Peek() == -1)
{
break; // We've reached the end of the string!
}
// Read the next line.
line = sr.ReadToCrLf();
if (isSmtpResponse)
{
// Diagnostic code is an SMTP response so look for SMTP response line.
if (Regex.IsMatch(line, @"\d{3}(-|\s)"))
{
diagnosticCode.AppendLine(line);
}
else // Not a SMTP response line so must be next NDR line.
{
foundNextLine = true;
}
}
else
{
// Non SMTP response. If first char is whitespace then it's part of the disagnostic-code otherwise it isn't.
if (char.IsWhiteSpace(line[0]))
{
diagnosticCode.AppendLine(line);
}
else
{
foundNextLine = true;
}
}
}
}
else
{
// We haven't found a diagnostic-code line.
// Check to see if we have found a status field.
if (line.StartsWith(StatusFieldName, StringComparison.OrdinalIgnoreCase))
{
status = line.Substring(StatusFieldName.Length).TrimEnd();
}
// If there is more of the string to read then read the next line, otherwise set line to string.empty.
if (sr.Peek() > -1)
{
line = sr.ReadToCrLf();
}
else
{
line = string.Empty;
}
}
}
}
// Process what we've managed to find...
// Diagnostic-Code
if (!string.IsNullOrWhiteSpace(diagnosticCode.ToString()))
{
if (ParseSmtpDiagnosticCode(diagnosticCode.ToString(), out bouncePair, out bounceMessage, out bounceIdentification))
{
return(true);
}
}
// Status
if (!string.IsNullOrWhiteSpace(status))
{
// If there's an NDR code in the Status value, use it.
Match m = Regex.Match(status, RegexPatterns.NonDeliveryReportCode, RegexOptions.ExplicitCapture);
if (m.Success)
{
bouncePair = BounceRulesManager.Instance.ConvertNdrCodeToMantaBouncePair(m.Value);
bounceMessage = m.Value;
bounceIdentification.BounceIdentifier = BounceIdentifier.NdrCode;
bounceIdentification.MatchingValue = m.Value;
return(true);
}
}
// If we've not already returned from this method, then we're still looking for an explanation
// for the bounce so parse the entire message as a string.
if (ParseBounceMessage(message, out bouncePair, out bounceMessage, out bounceIdentification))
{
return(true);
}
// Nope - no clues relating to why the bounce occurred.
bouncePair.BounceType = MantaBounceType.Unknown;
bouncePair.BounceCode = MantaBounceCode.Unknown;
bounceMessage = string.Empty;
bounceIdentification.BounceIdentifier = BounceIdentifier.NotIdentifiedAsABounce;
bounceIdentification.MatchingValue = string.Empty;
return(false);
}
