Issue a custom command to POP3 server

You can send any command to POP3 server using Mail.dll and receive servers’s response easy.

In this example we will issue LIST command. LIST command is used to check the email size without downloading it from the POP3 server.

There are 2 versions of the LIST command. First takes message number parameter:

LIST messageNumber

We are asking for specific message here, which means that we expect to receive single line response.

Remember that message numbers on POP3 servers start from 1.

// C# version

using System;
using Limilabs.Client.POP3;

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

            Pop3Response response = pop3.SendCommand("LIST " + 1);

            // We expect string in following format: "0 32768"
            string sizeInBytes = response.Message.Split(' ')[1];

            Console.WriteLine(sizeInBytes);
            pop3.Close();
        }
    }
};

' VB.NET version

Imports System
Imports Limilabs.Client.POP3

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

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

            Dim response As Pop3Response = pop3.SendCommand("LIST " + 1)

            ' We expect string in following format: "0 32768"
            Dim sizeInBytes As String = response.Message.Split(" "c)(1)

            Console.WriteLine(sizeInBytes)
            pop3.Close()
        End Using

    End Sub
End Module

Second version is LIST command without any arguments:

LIST

It gets the size of every message that is currently stored on the POP3 server – server replies with multi-line response:

// C# version

using System;
using Limilabs.Mail;
using Limilabs.Client.POP3;

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

            Pop3Response response = pop3.SendMultiLineCommand("LIST");

            foreach(string line in response.GetLines())
            {
                // We expect following format: "0 32768"
                string[] tmp = line.Split(' ');
                Console.WriteLine("Message number {0} is {1} bytes long.",
                                  tmp[0],
                                  tmp[1]);
            }
            pop3.Close();
        }
    }
};

' VB.NET version

Imports System
Imports Limilabs.Client.POP3

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

        Using pop3 As New Pop3()
            pop3.Connect("server.company.com")
            pop3.Login("user", "password")

            Dim response As Pop3Response = pop3.SendMultiLineCommand("LIST")

            For Each line As String In response.GetLines()
                ' We expect following format: "0 32768"
                Dim tmp As String() = line.Split(" "c)
                Console.WriteLine("Message number {0} is {1} bytes long.", tmp(0), tmp(1))
            Next
            pop3.Close()
        End Using

    End Sub
End Module

Tags: C# Email component POP3 POP3 component VB.NET