You could use the Outlook Redemption library which is capable of opening PST and extracting messages as .EML (among other formats). Redemption is a COM Object (32 or 64 bit) that can be used in C# without any problem. Here is a Console Application sample code that demonstrates this:
using System;
using System.IO;
using System.Text;
using Redemption;
namespace DumpPst
{
class Program
{
static void Main(string[] args)
{
// extract 'test.pst' in the 'test' folder
ExtractPst("test.pst", Path.GetFullPath("test"));
}
public static void ExtractPst(string pstFilePath, string folderPath)
{
if (pstFilePath == null)
throw new ArgumentNullException("pstFilePath");
RDOSession session = new RDOSession();
RDOPstStore store = session.LogonPstStore(pstFilePath);
ExtractPstFolder(store.RootFolder, folderPath);
}
public static void ExtractPstFolder(RDOFolder folder, string folderPath)
{
if (folder == null)
throw new ArgumentNullException("folder");
if (folderPath == null)
throw new ArgumentNullException("folderPath");
if (folder.FolderKind == rdoFolderKind.fkSearch)
return;
if (!Directory.Exists(folderPath))
{
Directory.CreateDirectory(folderPath);
}
foreach(RDOFolder child in folder.Folders)
{
ExtractPstFolder(child, Path.Combine(folderPath, ToFileName(child.Name)));
}
foreach (var item in folder.Items)
{
RDOMail mail = item as RDOMail;
if (mail == null)
continue;
mail.SaveAs(Path.Combine(folderPath, ToFileName(mail.Subject)) + ".eml", rdoSaveAsType.olRFC822);
}
}
/// <summary>
/// Converts a text into a valid file name.
/// </summary>
/// <param name="fileName">The file name.</param>
/// <returns>
/// A valid file name.
/// </returns>
public static string ToFileName(string fileName)
{
return ToFileName(fileName, null, null);
}
/// <summary>
/// Converts a text into a valid file name.
/// </summary>
/// <param name="fileName">The file name.</param>
/// <param name="reservedNameFormat">The reserved format to use for reserved names. If null '_{0}_' will be used.</param>
/// <param name="reservedCharFormat">The reserved format to use for reserved characters. If null '_x{0}_' will be used.</param>
/// <returns>
/// A valid file name.
/// </returns>
public static string ToFileName(string fileName, string reservedNameFormat, string reservedCharFormat)
{
if (fileName == null)
throw new ArgumentNullException("fileName");
if (string.IsNullOrEmpty(reservedNameFormat))
{
reservedNameFormat = "_{0}_";
}
if (string.IsNullOrEmpty(reservedCharFormat))
{
reservedCharFormat = "_x{0}_";
}
if (Array.IndexOf(ReservedFileNames, fileName.ToLowerInvariant()) >= 0 ||
IsAllDots(fileName))
return string.Format(reservedNameFormat, fileName);
char[] invalid = Path.GetInvalidFileNameChars();
StringBuilder sb = new StringBuilder(fileName.Length);
foreach (char c in fileName)
{
if (Array.IndexOf(invalid, c) >= 0)
{
sb.AppendFormat(reservedCharFormat, (short)c);
}
else
{
sb.Append(c);
}
}
string s = sb.ToString();
// directory limit is 255
if (s.Length > 254)
{
s = s.Substring(0, 254);
}
if (string.Equals(s, fileName, StringComparison.Ordinal))
{
s = fileName;
}
return s;
}
private static bool IsAllDots(string fileName)
{
foreach (char c in fileName)
{
if (c != '.')
return false;
}
return true;
}
private static readonly string[] ReservedFileNames = new[]
{
"con", "prn", "aux", "nul",
"com0", "com1", "com2", "com3", "com4", "com5", "com6", "com7", "com8", "com9",
"lpt0", "lpt1", "lpt2", "lpt3", "lpt4", "lpt5", "lpt6", "lpt7", "lpt8", "lpt9"
};
}
}