Get email Headers from an Outlook MailItem

While working on a VSTO add-in for Microsoft Outlook, I came across the need to access the headers of an email, to parse out X-CustomProperty tags that were put in by an application that sent the emails. However, I couldn’t find a Headers property in the Outlook object model, so below is an attempt to create one.

The Regex used is courtesy of John Gietzen’s answer on this stackoverflow question.

using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using Microsoft.Office.Interop.Outlook;

public static class MailItemExtensions
{
    private const string HeaderRegex =
        @"^(?<header_key>[-A-Za-z0-9]+)(?<seperator>:[ \t]*)" +
            "(?<header_value>([^\r\n]|\r\n[ \t]+)*)(?<terminator>\r\n)";
    private const string TransportMessageHeadersSchema =
        "http://schemas.microsoft.com/mapi/proptag/0x007D001E";

    public static string[] Headers(this MailItem mailItem, string name)
    {
        var headers = mailItem.HeaderLookup();
        if (headers.Contains(name))
            return headers[name].ToArray();
        return new string[0];
    }

    public static ILookup<string, string> HeaderLookup(this MailItem mailItem)
    {
        var headerString = mailItem.HeaderString();
        var headerMatches = Regex.Matches
            (headerString, HeaderRegex, RegexOptions.Multiline).Cast<Match>();
        return headerMatches.ToLookup(
            h => h.Groups["header_key"].Value,
            h => h.Groups["header_value"].Value);
    }

    public static string HeaderString(this MailItem mailItem)
    {
        return (string)mailItem.PropertyAccessor
            .GetProperty(TransportMessageHeadersSchema);
    }
}

Sample usage:

string[] preparedByArray = mailItem.Headers("X-PreparedBy");
string preparedBy;
if (preparedByArray.Length == 1)
    preparedBy = preparedByArray[0];
else 
    preparedBy = "";

string allHeaders = mailItem.HeaderString();

Edit 2011/08/05:
Thanks to Rob for the heads-up. I updated the code to return a Lookup instead of a Dictionary – this handles the case of multiple headers with the same name.

How to filter select list options

Here’s a jQuery extension method to filter the elements of a select list (option tags). It binds to a textbox, and as you type in the textbox the select list gets filtered to match what you are typing.

jQuery.fn.filterByText = function(textbox, selectSingleMatch) {
  return this.each(function() {
    var select = this;
    var options = [];
    $(select).find('option').each(function() {
      options.push({value: $(this).val(), text: $(this).text()});
    });
    $(select).data('options', options);
    $(textbox).bind('change keyup', function() {
      var options = $(select).empty().scrollTop(0).data('options');
      var search = $.trim($(this).val());
      var regex = new RegExp(search,'gi');

      $.each(options, function(i) {
        var option = options[i];
        if(option.text.match(regex) !== null) {
          $(select).append(
             $('<option>').text(option.text).val(option.value)
          );
        }
      });
      if (selectSingleMatch === true && 
          $(select).children().length === 1) {
        $(select).children().get(0).selected = true;
      }
    });
  });
};

Parameters:

  • textbox
    This could be a jQuery selector, a jQuery object, or a DOM object.
  • selectSingleMatch
    This is optional, if you set it to true, when the filtered list includes only one item, that item will be automatically selected.

For example:

$(function() {
  $('#select').filterByText($('#textbox'), true);
});  

Live example (or in a new window):

You can play around with it on jsbin: http://jsbin.com/egogeh/edit

What it does:

When you invoke the function on a select object, it finds all child option tags and saves their text and values into an array. This array is saved to the select object itself as a HTML5 custom data attribute, called data-options. Then, when a change or keyup event fires on the associated textbox, the select list is emptied, and for any entries in the array that match the search text a new option element is created.

Edit 2012-10-15: Added ScrollTop(0) to improve the way it works with long lists, thanks to a comment by xarel below.