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.
