Logging communication using LogWriter 

Communication logs are very useful when troubleshooting issues at the SMTP protocol on communication level. Whenever you run into a problem, a log makes it possible to see what is going on.

To start logging, just add the following line into your code (just after creating the Smtp client object):

// create client instance
// ...

// start logging to a file
client.LogWriter = new Rebex.FileLogWriter(@"C:\MyData\log.txt");

' create client instance
' ...

' start logging to a file
client.LogWriter = New Rebex.FileLogWriter("C:\MyData\log.txt")

A sample SMTP log file :

2015-11-03 17:08:51.150 Opening log file.
2015-11-03 17:08:51.150 Using FileLogWriter version 2.0.0.0.
2015-11-03 17:08:51.156 INFO Smtp(1)[6] Info: Connecting to smtpserver.local:25 using Smtp 2.0.0.0.
2015-11-03 17:08:51.279 INFO Smtp(1)[6] Response: 220 smtpserver.local Microsoft ESMTP MAIL Service ready at Fri, 3 Oct 2014 17:08:50 +0200
2015-11-03 17:08:51.284 INFO Smtp(1)[6] Command: EHLO myworkstation.local
2015-11-03 17:08:51.284 INFO Smtp(1)[6] Response: 250-wsmtpserver.local Hello [192.168.1.2]
2015-11-03 17:08:51.284 INFO Smtp(1)[6] Response: 250-SIZE
2015-11-03 17:08:51.284 INFO Smtp(1)[6] Response: 250-PIPELINING
2015-11-03 17:08:51.284 INFO Smtp(1)[6] Response: 250-DSN
2015-11-03 17:08:51.284 INFO Smtp(1)[6] Response: 250-ENHANCEDSTATUSCODES
2015-11-03 17:08:51.284 INFO Smtp(1)[6] Response: 250-STARTTLS
2015-11-03 17:08:51.284 INFO Smtp(1)[6] Response: 250-X-ANONYMOUSTLS
2015-11-03 17:08:51.285 INFO Smtp(1)[6] Response: 250-AUTH NTLM LOGIN
2015-11-03 17:08:51.285 INFO Smtp(1)[6] Response: 250-X-EXPS GSSAPI NTLM
2015-11-03 17:08:51.285 INFO Smtp(1)[6] Response: 250-8BITMIME
2015-11-03 17:08:51.285 INFO Smtp(1)[6] Response: 250-BINARYMIME
2015-11-03 17:08:51.285 INFO Smtp(1)[6] Response: 250-CHUNKING
2015-11-03 17:08:51.285 INFO Smtp(1)[6] Response: 250-XEXCH50
2015-11-03 17:08:51.285 INFO Smtp(1)[6] Response: 250-XRDST
2015-11-03 17:08:51.285 INFO Smtp(1)[6] Response: 250 XSHADOW
2015-11-03 17:08:51.300 INFO Smtp(1)[6] Command: QUIT

Log verbosity levels 

There are several levels of log verbosity:

• Error - logs error messages only
• Info - default level; logs important informative messages as well
• Debug - logs all messages useful for debugging purposes
• Verbose - very detailed log for advanced analysis; logs content of communication packets
  Warning: At the Verbose level, user credentials are written to the log as well.

To specify a log level, just pass an argument to FileLogWriter's constructor:

// create client instance
// ...

// start logging to a file at debug level
client.LogWriter = new Rebex.FileLogWriter(
    @"C:\MyData\log.txt", Rebex.LogLevel.Debug);

' create client instance
' ...

' start logging to a file at debug level
client.LogWriter = New Rebex.FileLogWriter("C:\MyData\log.txt", Rebex.LogLevel.Debug)

Built-in log writers 

Text file

To log into a text file, use FileLogWriter:

// create client instance
// ...

// start logging to a file at debug level
client.LogWriter = new Rebex.FileLogWriter(
    @"C:\MyData\log.txt", Rebex.LogLevel.Debug);

' create client instance
' ...

' start logging to a file at debug level
client.LogWriter = New Rebex.FileLogWriter("C:\MyData\log.txt", Rebex.LogLevel.Debug)

.NET trace listener

To log to .NET Trace Listeners, use TraceLogWriter:

// create client instance
// ...

// start logging to subscribed trace listeners
client.LogWriter = new Rebex.TraceLogWriter(Rebex.LogLevel.Debug);

' create client instance
' ...

' start logging to subscribed trace listeners
client.LogWriter = New Rebex.TraceLogWriter(Rebex.LogLevel.Debug)

Standard output stream

To log to the standard output stream, use ConsoleLogWriter:

// create client instance
// ...

// start logging to the standard output stream at debug level
client.LogWriter = new Rebex.ConsoleLogWriter(Rebex.LogLevel.Debug);

' create client instance
' ...

' start logging to the standard output stream at debug level
client.LogWriter = New Rebex.ConsoleLogWriter(Rebex.LogLevel.Debug)

Logging to multiple log writers

To log to more log writers at the same time, use TeeLogWriter:

var consoleLogWriter = new Rebex.ConsoleLogWriter(Rebex.LogLevel.Debug);
var fileLogWriter = new Rebex.FileLogWriter(@"C:\MyData\log.txt", Rebex.LogLevel.Info);

// start logging to both console and file log writers
client.LogWriter = new Rebex.TeeLogWriter(consoleLogWriter, fileLogWriter);

Dim consoleLogWriter = New Rebex.ConsoleLogWriter(Rebex.LogLevel.Debug)
Dim fileLogWriter = New Rebex.FileLogWriter("C:\MyData\log.txt", Rebex.LogLevel.Debug)

' start logging to both console and file log writers
client.LogWriter = New Rebex.TeeLogWriter(consoleLogWriter, fileLogWriter)

Writing custom log writers 

To implement your own LogWriter, either implement Rebex.ILogWriter interface or simply derive a class from Rebex.LogWriterBase:

// Sample log writer that logs to the standard error output stream
public class MyLogWriter : LogWriterBase
{
    protected override void WriteMessage(string message)
    {
        Console.Error.WriteLine("Rebex: {0}", message);
    }
}

' Sample log writer that logs to the standard error output stream
Public Class MyLogWriter
    Inherits LogWriterBase
    Protected Overrides Sub WriteMessage(message As String)
        Console.Error.WriteLine("Rebex: {0}", message)
    End Sub
End Class