Access custom email header using IMAP

Most common email headers like From, Subject, Date, To, Cc etc. are exposed by IMail interface as properties. Those properties contain parsed information and return strong typed objects like DateTime‘s, string collections, MailAddress collections.

There are times however that you need to access non-standard email header. Good example is a need to get a spam value that your IMAP server assigns to every email by inserting additional ‘x-spam’ header.

Mail.dll MIME and S/MIME parser allows users to access entire MIME tree of the message. IMail.Document property returns MIME document that represent this email message. You can use IMail.Document.Root.Headers collection to access any non-standard and standard header.

If you are using IMAP client you can also search IMAP server for messages that have specified header or have specified value in header.

If you only need to access email headers, consider using GetHeadersByUID method, which doesn’t download entire message from IMAP server just headers. The sample below on the other hand downloads entire message.

// C# version

using System;
using Limilabs.Mail;
using Limilabs.Client.IMAP;

class Program
{
    static void Main(string[] args)
    {
        using (Imap imap = new Imap())
        {
            imap.Connect("imap.example.com");    // or ConnectSSL for SSL
            imap.Login("user", "password");

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

                // Get custom header:
                string header = email.Document.Root.Headers["x-spam"];
                Console.WriteLine("x-spam: {0}", header);
            }
            imap.Close();
        }
    }
};

' VB.NET version

Imports System
Imports Limilabs.Mail
Imports Limilabs.Client.IMAP

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

        Using imap As New Imap()
            imap.Connect("imap.example.com")    ' or ConnectSSL for SSL
            imap.Login("user", "password")

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

                ' Get custom header:
                Dim header As String = email.Document.Root.Headers("x-spam")
                Console.WriteLine("x-spam: {0}", header)
            Next
            imap.Close()
        End Using

    End Sub
End Module

Tags: C# IMAP IMAP component VB.NET