1. Sign in to Gmail.
2. Click the gear icon in the upper-right and select Mail settings .
3. Click Forwarding and POP/IMAP.
4. SSelect Enable POP for all mail or Enable POP for mail that arrives from now on.
5. Now you are able to connect to your Gmail account with Mail.dll POP3 library.

Remember that Gmail only allows secure SSL connections so we need to use ConnectSSL method.

// C#

using (Imap client = new Imap())
{
    client.ConnectSSL("imap.example.org");
    client.UseBestLogin("user", "password");

    Console.WriteLine("Supported methods:");

    foreach (var method in client.SupportedAuthenticationMethods())
    {
        Console.WriteLine(method.Name);
    }

    Console.WriteLine("Supports CramMD5:");

    bool supportsCramMD5 = client.SupportedAuthenticationMethods()
        .Contains(ImapAuthenticationMethod.CramMD5);

    Console.WriteLine(supportsCramMD5);

    client.Close();
}

' VB.NET

Using client As New Imap()
    client.ConnectSSL("imap.example.org")
    client.UseBestLogin("user", "password")

    Console.WriteLine("Supported methods:")

    For Each method As ImapAuthenticationMethod In client.SupportedAuthenticationMethods()
	    Console.WriteLine(method.Name)
    Next

    Console.WriteLine("Supports CramMD5:")

    Dim supportsCramMD5 As Boolean = client.SupportedAuthenticationMethods() _
        .Contains(ImapAuthenticationMethod.CramMD5)

    Console.WriteLine(supportsCramMD5)

    client.Close()
End Using

For example Gmail produces following output:

Supported method s:
IMAP4rev1
UNSELECT
IDLE
NAMESPACE
QUOTA
ID
XLIST
CHILDREN
X-GM-EXT-1
UIDPLUS
COMPRESS

Supports CramMD5:
False

We take great care for the API to look similar for all protocols (IMAP, POP3, SMTP).

Here’s the sample for POP3:

// C#

using (Pop3 client = new Pop3())
{
    client.ConnectSSL("pop3.example.org");
    client.UseBestLogin("user", "password");

    Console.WriteLine("Supported methods:");

    foreach (var method in client.SupportedAuthenticationMethods())
    {
        Console.WriteLine(method.Name);
    }

    Console.WriteLine("Supports CramMD5:");

    bool supportsCramMD5 = client.SupportedAuthenticationMethods()
        .Contains(Pop3AuthenticationMethod.CramMD5);

    Console.WriteLine(supportsCramMD5);

    client.Close();
}

' VB.NET

Using client As New Pop3()
    client.ConnectSSL("pop3.example.org")
    client.UseBestLogin("user", "password")

    Console.WriteLine("Supported methods:")

    For Each method As Pop3AuthenticationMethod In client.SupportedAuthenticationMethods()
	    Console.WriteLine(method.Name)
    Next

    Console.WriteLine("Supports CramMD5:")

    Dim supportsCramMD5 As Boolean = client.SupportedAuthenticationMethods() _
        .Contains(Pop3AuthenticationMethod.CramMD5)

    Console.WriteLine(supportsCramMD5)

    client.Close()
End Using

Here’s the sample for SMTP:

// C#

using (Smtpclient = new Smtp())
{
    client.Connect("smtp.example.org");
    client.UseBestLogin("smtp", "password");

    Console.WriteLine("Supported methods:");

    foreach (var method in client.SupportedAuthenticationMethods())
    {
        Console.WriteLine(method.Name);
    }

    Console.WriteLine("Supports CramMD5:");

    bool supportsCramMD5 = client.SupportedAuthenticationMethods()
        .Contains(SmtpAuthenticationMethod.CramMD5);

    Console.WriteLine(supportsCramMD5);

    client.Close();
}

' VB.NET

Using client As New Smtp()
    client.Connect("smtp.example.org")
    client.UseBestLogin("user", "password")

    Console.WriteLine("Supported methods:")

    For Each method As SmtpAuthenticationMethod In client.SupportedAuthenticationMethods()
	    Console.WriteLine(method.Name)
    Next

    Console.WriteLine("Supports CramMD5:")

    Dim supportsCramMD5 As Boolean = client.SupportedAuthenticationMethods() _
        .Contains(SmtpAuthenticationMethod.CramMD5)

    Console.WriteLine(supportsCramMD5)

    client.Close()
End Using

// C#

using (Imap client = new Imap())
{
    client.ConnectSSL("imap.example.org");
    client.UseBestLogin("user", "password");

    Console.WriteLine("Supported extensions:");

    foreach (ImapExtension extension in client.SupportedExtensions())
    {
        Console.WriteLine(extension.Name);
    }

    Console.WriteLine("Supports IDLE:");

    bool supportsIdle = client.SupportedExtensions()
        .Contains(ImapExtension.Idle);

    Console.WriteLine(supportsIdle);

    client.Close();
}

' VB.NET

Using client As New Imap()
    client.ConnectSSL("imap.example.org")
    client.UseBestLogin("user", "password")

    Console.WriteLine("Supported extensions:")

    For Each extension As ImapExtension In client.SupportedExtensions()
	    Console.WriteLine(extension.Name)
    Next

    Console.WriteLine("Supports IDLE:")

    Dim supportsIdle As Boolean = client.SupportedExtensions() _
        .Contains(ImapExtension.Idle)

    Console.WriteLine(supportsIdle)

    client.Close()
End Using

For example Gmail produces following output:

Supported extensions:
IMAP4rev1
UNSELECT
IDLE
NAMESPACE
QUOTA
ID
XLIST
CHILDREN
X-GM-EXT-1
UIDPLUS
COMPRESS

Supports IDLE:
True

We take great care for the API to look similar for all protocols (IMAP, POP3, SMTP).

Here’s the sample for POP3:

// C#

using (Pop3 client = new Pop3())
{
    client.ConnectSSL("pop3.example.org");
    client.UseBestLogin("user", "password");

    Console.WriteLine("Supported extensions:");

    foreach (Pop3Extension extension in client.SupportedExtensions())
    {
        Console.WriteLine(extension.Name);
    }

    Console.WriteLine("Supports TOP:");

    bool supportsTop= client.SupportedExtensions()
        .Contains(Pop3Extension.Top);

    Console.WriteLine(supportsTop);

    client.Close();
}

' VB.NET

Using client As New Pop3()
    client.ConnectSSL("pop3.example.org")
    client.UseBestLogin("user", "password")

    Console.WriteLine("Supported extensions:")

    For Each extension As Pop3Extension In client.SupportedExtensions()
	    Console.WriteLine(extension.Name)
    Next

    Console.WriteLine("Supports TOP:")

    Dim supportsTop As Boolean = client.SupportedExtensions() _
        .Contains(Pop3Extension.Top)

    Console.WriteLine(supportsTop)

    client.Close()
End Using

Here’s the sample for SMTP:

// C#

using (Smtpclient = new Smtp())
{
    client.Connect("smtp.example.org");
    client.UseBestLogin("smtp", "password");

    Console.WriteLine("Supported extensions:");

    foreach (SmtpExtension  extension in client.SupportedExtensions())
    {
        Console.WriteLine(extension.Name);
    }

    Console.WriteLine("Supports STARTTLS:");

    bool supportsStartTLS = client.SupportedExtensions()
        .Contains(SmtpExtension.StartTLS);

    Console.WriteLine(supportsStartTLS);

    client.Close();
}

' VB.NET

Using client As New Smtp()
    client.Connect("smtp.example.org")
    client.UseBestLogin("user", "password")

    Console.WriteLine("Supported extensions:")

    For Each extension As SmtpExtension In client.SupportedExtensions()
	    Console.WriteLine(extension.Name)
    Next

    Console.WriteLine("Supports STARTTLS:")

    Dim supportsStartTLS As Boolean = client.SupportedExtensions() _
        .Contains(SmtpExtension.StartTLS)

    Console.WriteLine(supportsStartTLS)

    client.Close()
End Using

“The unique-id of a message is an arbitrary server-determined string, [...], which uniquely identifies a message within a maildrop and which persists across sessions.”

“The server should never reuse an unique-id in a given maildrop, for as long as the entity using the unique-id exists.”

So in theory if the email is deleted server may reuse the same unique-id.

“While it is generally preferable for server implementations to store arbitrarily assigned unique-ids in the maildrop, this specification is intended to permit unique-ids to be calculated as a hash of the message.

Clients should be able to handle a situation where two identical copies of a message in a maildrop have the same unique-id.”

Mail.dll will not throw exception in such case, but please note that as internally Mail.dll uses dictionaries to store unique-ids, Pop3.GetAll() method will not return duplicates.

If you are having the problems parsing a single message please go here

1.
First please check if you have the latest version installed.

2.
Please identify the command/set of commands that cause problems.

3.
Enable logging for Mail.dll clients:

// C# version:

Log.Enabled = true;

// VB.NET version:

Log.Enabled = True

You can observe standard Visual Studio trace output or add a custom listener to Trace.Listeners collection.

You can also enable logging using App.config file:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <system.diagnostics>
      <switches>
        <add name="Mail.dll" value="True" />
      </switches>
    </system.diagnostics>
</configuration>

You can create your custom TraceListener that writes log to file:

// C# version:

internal class MyListener : TextWriterTraceListener
{
    public MyListener(string fileName)
        : base(fileName)
    {
    }

    public override void Write(string message, string category)
    {
        if (category == "Mail.dll")
            base.Write(message, category);
    }

    public override void WriteLine(string message, string category)
    {
        if (category == "Mail.dll")
            base.WriteLine(message, category);
    }
}

' VB.NET version

Friend Class MyListener
	Inherits TextWriterTraceListener
	Public Sub New(fileName As String)
		MyBase.New(fileName)
	End Sub

	Public Overrides Sub Write(message As String, category As String)
		If category = "Mail.dll" Then
			MyBase.Write(message, category)
		End If
	End Sub

	Public Overrides Sub WriteLine(message As String, category As String)
		If category = "Mail.dll" Then
			MyBase.WriteLine(message, category)
		End If
	End Sub
End Class

…then add it to Listeners collection:

// C# version:

Log.Enabled = true;
Trace.Listeners.Add(new MyListener(@"c:mail_log.txt"));
Trace.AutoFlush = true;

// VB.NET version:

Log.Enabled = True
Trace.Listeners.Add(New MyListener("c:mail_log.txt"))
Trace.AutoFlush = True

4.
Perform the operations that cause the problems, and save the log to file.
You can remove username and password, but please do not modify the file extensively. If you do, it may be impossible to reproduce the issue.
In particular do not change new line format nor encoding.

5.
Please answer following questions:

• What exception are you getting?
• What is the exception stack trace?
• What is the exception message?
• What result you expect?
• What result are you getting?
• Which .NET Framework version are you using?
• Is it console, windows forms, windows service or web application?
• If it is possible please attach the source code you are using

6.
Finally please zip the log file and send it as attachment, along with all the answers to .

Thanks!

If you are having the problems issuing IMAP, POP3, or SMTP command please go here.

1.
First please check if you have the latest version installed.

2.
Please identify unique id (UID) of the message you are having problems with.

3.
Next step is to download entire message and save it as raw eml file.
Note that you are not parsing the email so you don’t need to use MailBuilder and IMail classes.

IMAP version:

// C# code

long uid = 12345;

using (Imap imap = new Imap())
{
    imap.Connect("server");
    // imap.ConnectSSL("server"); // if you need SSL connection.
    imap.Login("user", "password");
    imap.SelectInbox();

    string eml = imap.GetMessageByUID(uid);
    string fileName = string.Format("c:\email_{0}.eml", uid);
    File.WriteAllText(fileName, eml, Encoding.UTF8);

    imap.Close();
}

' VB.NET code

Dim uid As Long = 12345

Using imap As New Imap()
	imap.Connect("server")
	' imap.ConnectSSL("server") ' if you need SSL connection.
	imap.Login("user", "password")
	imap.SelectInbox()

	Dim eml As String = imap.GetMessageByUID(uid)
	Dim fileName As String = String.Format("c:\email_{0}.eml", uid)
	File.WriteAllText(fileName, eml, Encoding.UTF8)

	imap.Close()
End Using

POP3 version:

// C# code

string uid = "12345";

using (Pop3 pop3 = new Pop3())
{
    pop3.Connect("server");
    // pop3.ConnectSSL("server"); // if you need SSL connection.
    pop3.Login("user", "password");

    string eml = pop3.GetMessageByUID(uid));
    string fileName = string.Format("c:\email_{0}.eml", uid);
    File.WriteAllText(fileName, eml, Encoding.UTF8);

    pop3.Close();
}

' VB.NET code

Dim uid As String = "12345"

Using pop3 As New Pop3()
	pop3.Connect("server")
	' pop3.ConnectSSL("server"); ' if you need SSL connection.
	pop3.Login("user", "password")

	Dim eml As String = pop3.GetMessageByUID(uid)
	Dim fileName As String = String.Format("c:\email_{0}.eml", uid)
	File.WriteAllText(fileName, eml, Encoding.UTF8)

	pop3.Close()
End Using

4.
Please answer following questions:

• What exception are you getting?
• What is the exception stack trace?
• What is the exception message?
• What result you expect?
• What result are you getting?
• Which .NET Framework version are you using?
• Is it console, windows forms, windows service or web application?
• If it is possible please attach the source code you are using

5.
Finally please zip the eml file and send it as attachment, along with all the answers to .

Thanks!

Most email providers (like Gmail, Hotmail, Yahoo and others) use default ports.

Parameterless Connect() and ConnectSSL() and fluent interface use those ports.

Default ports for email protocols are:

Please ask your email server administrator for server, port, and SSL usage,
if those are not standard there is no way you can guess them.

Please also make sure that:

• you are using correct client class with protocol and port you plan to use (Pop3 class with POP3 protocol, Imap class with IMAP, and Smtp class with SMTP protocol)
• the protocol you are trying to use is enabled on the server. Exchange or Gmail can have some protocols disabled by default
• you are using ConnectSSL when you require SSL, and Connect when you don’t
• firewall and antivirus software are disabled or configured correctly

Following articles can help you with that:
How to enable POP3 for Gmail
How to enable IMAP for Gmail
How to enable IMAP for Exchange

Establishing connection using default port is simple:

// C#

client.Connect("mail.example.com");

' VB.NET

client.Connect("mail.example.com")

or if SSL is enabled:

// C#

client.ConnectSSL("mail.example.com");

' VB.NET

client.ConnectSSL("mail.example.com")

If you need to specify different port just use overloaded version of Connect method:

// C#

client.Connect("mail.example.com", 999);

' VB.NET

client.Connect("mail.example.com", 999)

If you are using SSL:

// C#

client.ConnectSSL("mail.example.com", 999);

' VB.NET

client.ConnectSSL("mail.example.com", 999)

If you need to specify different port using fluent interface use OnPort() method:

// C# version

Mail.Text(@"Hello")
  .To("to@mail.com")
  .From("from@mail.com")
  .Subject("Subject")
  .UsingNewSmtp()
  .Server(_server)
  .WithSSL()
  .OnPort(443)
  .WithCredentials("user", "password")
  .Send();

Some servers require explicit SSL (Usually this triggers “The handshake failed due to an unexpected packet format” exception) please look at following articles for details:

• Use SSL with IMAP
• Use SSL with POP3
• Use SSL with SMTP

If you have problems with SSL, your server may be using self-signed certificates:

• The remote certificate is invalid according to the validation procedure

Again when in doubt please ask your email server administrator for server, port, and SSL usage.

// C# version:

Log.Enabled = true;

// VB.NET version:

Log.Enabled = True

You can observe standard Visual Studio trace output or add a custom listener to Trace.Listeners collection.

You can also enable logging using App.config file:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <system.diagnostics>
      <switches>
        <add name="Mail.dll" value="True" />
      </switches>
    </system.diagnostics>
</configuration>

You can create your custom TraceListener that writes log to file:

// C# version:

internal class MyListener : TextWriterTraceListener
{
    public MyListener(string fileName)
        : base(fileName)
    {
    }

    public override void Write(string message, string category)
    {
        if (category == "Mail.dll")
            base.Write(message, category);
    }

    public override void WriteLine(string message, string category)
    {
        if (category == "Mail.dll")
            base.WriteLine(message, category);
    }
}

' VB.NET version

Friend Class MyListener
	Inherits TextWriterTraceListener
	Public Sub New(fileName As String)
		MyBase.New(fileName)
	End Sub

	Public Overrides Sub Write(message As String, category As String)
		If category = "Mail.dll" Then
			MyBase.Write(message, category)
		End If
	End Sub

	Public Overrides Sub WriteLine(message As String, category As String)
		If category = "Mail.dll" Then
			MyBase.WriteLine(message, category)
		End If
	End Sub
End Class

…then add it to Listeners collection:

// C# version:

Log.Enabled = true;
Trace.Listeners.Add(new MyListener(@"c:mail_log.txt"));
Trace.AutoFlush = true;

// VB.NET version:

Log.Enabled = True
Trace.Listeners.Add(New MyListener("c:mail_log.txt"))
Trace.AutoFlush = True

// C#

client.Connect("mail.example.com");

' VB.NET

client.Connect("mail.example.com")

If you need to specify different port just use overloaded version of Connect method:

// C#

client.Connect("mail.example.com", 999);
// -or-
client.Connect("mail.example.com", 999, false);

' VB.NET

client.Connect("mail.example.com", 999)
' -or-
client.Connect("mail.example.com", 999, False)

If you are using SSL:

// C#

client.ConnectSSL("mail.example.com", 999);
// -or-
client.Connect("mail.example.com", 999, true);

' VB.NET

client.ConnectSSL("mail.example.com", 999)
' -or-
client.Connect("mail.example.com", 999, True)

// C# version

using System;
using Lesnikowski.Client;
using Lesnikowski.Mail;
using Lesnikowski.Mail.Headers;
using Lesnikowski.Mail.Headers.Constants;

class Program
{
    static void Main(string[] args)
    {
        using (Pop3 pop3 = new Pop3())
        {
            pop3.ConnectSSL("server.example.com");
            pop3.Login("user", "password");

            MailBuilder builder = new MailBuilder();
            foreach (string uid in pop3.GetAll())
            {
                string eml = pop3.GetMessageByUID(uid);
                IMail email = builder.CreateFromEml(eml);
                Console.WriteLine("subject: {0}", email.Subject);
            }
            pop3.Close();
        }
    }
};

' VB.NET version

Imports Lesnikowski.Client
Imports Lesnikowski.Mail
Imports Lesnikowski.Mail.Headers
Imports Lesnikowski.Mail.Headers.Constants

Public Module Module1
    Public Sub Main(ByVal args As String())

        Using pop3 As New Pop3()
            pop3.ConnectSSL("server.example.com")
            pop3.Login("user", "password")

            Dim builder As New MailBuilder()
            For Each uid As String In pop3.GetAll()
                Dim eml As String = pop3.GetMessageByUID(uid)
                Dim email As IMail = builder.CreateFromEml(eml)
                Console.WriteLine("subject: {0}", email.Subject)
            Next
            pop3.Close()
        End Using

    End Sub
End Module

Explicit mode:

// C# version

using System;
using Lesnikowski.Client;
using Lesnikowski.Mail;
using Lesnikowski.Mail.Headers;
using Lesnikowski.Mail.Headers.Constants;

class Program
{
    static void Main(string[] args)
    {
        using (Pop3 pop3 = new Pop3())
        {
            pop3.Connect("server.example.com");

            pop3.STLS();

            pop3.Login("user", "password");

            MailBuilder builder = new MailBuilder();
            foreach (string uid in pop3.GetAll())
            {
                string eml = pop3.GetMessageByUID(uid);
                IMail email = builder.CreateFromEml(eml);
                Console.WriteLine("subject: {0}", email.Subject);
            }
            pop3.Close();
        }
    }
};

' VB.NET version

Imports Lesnikowski.Client
Imports Lesnikowski.Mail
Imports Lesnikowski.Mail.Headers
Imports Lesnikowski.Mail.Headers.Constants

Public Module Module1
    Public Sub Main(ByVal args As String())

        Using pop3 As New Pop3()
            pop3.Connect("server.example.com")

            pop3.STLS()

            pop3.Login("user", "password")

            Dim builder As New MailBuilder()
            For Each uid As String In pop3.GetAll()
                Dim eml As String = pop3.GetMessageByUID(uid)
                Dim email As IMail = builder.CreateFromEml(eml)
                Console.WriteLine("subject: {0}", email.Subject)
            Next
            pop3.Close()
        End Using

    End Sub
End Module