Easily automate Microsoft Outlook via .NET

by Tony Patton | Sep 06, 2005 3:31:00 PM

Tags: Groupware, Microsoft Office, Tony Patton, Outlook Object Model, Microsoft Corp., Microsoft .NET, Microsoft Outlook, .NET Newsletter

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Takeaway: The interoperability between the .NET platform and Microsoft Office, particularly Outlook, greatly expands developers' options. Learn how to take advantage of Outlook in your next development endeavor.

In recent articles I've covered working with various pieces of the Microsoft Office Suite including Word and Excel. Today, I'll continue the concept by manipulating Microsoft Outlook via Microsoft .NET code.

Working with Outlook

As with other Microsoft Office products, Visual Basic for Applications (VBA) is utilized. Consequently, a little COM (Component Object Model) knowledge comes in handy. However, the .NET COM interop feature simplifies the process for .NET developers. Thus, you can easily utilize COM objects within a .NET application.

The Outlook object model exposes many features of the Outlook environment. This includes the following functionality:

E-mail: create, send, and manipulate mail items
Contacts database: Utilize the Outlook contacts databases. You may add new contacts, edit existing, or integrate with other applications like creating a letter via Word and information from an Outlook contact.
Calendar: create, edit, delete, and manipulate individual calendar entries
Notes and Tasks: Interact with the notes and tasks portions of Outlook
Outlook user interface: Control or manipulate explorers, inspectors, command bars, and so forth.

Microsoft supplies an interop assembly, which ships with Outlook 2003. This assembly, named Microsoft.Office.Interop.Outlook.dll, resides in the Global Assembly Cache under the name Microsoft.Office.Interop.Outlook.dll. To reference this assembly from Visual Studio .NET 2003, access the COM tab from the Add References dialog box and select Microsoft Outlook 11.0 Object Library.

Outlook object model

Outlook exposes an overwhelming number of objects with associated methods, properties, and so forth. Thankfully, their functions are documented and available with an installation of Microsoft Office. The help files are located on the hard drive (if help is installed) in the following path:

<drive letter>:\Program Files\Microsoft Office\OFFICE11\1033

There will be help files for all Office applications installed. A drawback of the help documentation is all code examples are presented via VBScript, so you will have to be aware of this difference when trying to apply to the .NET Framework. With that said, let's take a closer look at individual entities within the Outlook object model. We'll focus on the following items:

Application: The Outlook application environment. This is the root object necessary to work with Outlook.
Namespace: The Namespace object represents the messaging service provider. The MAPI namespace is required to gain access to Outlook folders and items.
MailItem: The MailItem object allows you to work with Outlook mail memos. There are various item objects available to work with the various item types including notes, calendar entries, contacts, and so forth.
MAPIFolder: If you use Outlook, you're familiar with folders. (I'm often chastised for my organized Outlook inbox, with everything filed in the appropriate folder.) The MAPIFolder object provides a vehicle for working with mail folders.

Let's put these objects to use by creating and sending e-mails via Outlook.

Sending e-mail

In the next example, a simple mail message is created and sent via Outlook. Listing A uses C#, while Listing B shows the example with VB.NET.

A few notes on the code:

A copy of the mail message is copied to the Drafts folder for the purpose of demonstrating how placing a message in a folder works. The olDefaultFolders object contains a list of the default folders included with Outlook.
The creation of a mail item uses the CreateItem method of the Outlook.Application class. The call to this method requires a cast to the necessary Item type (in this case, MailItem).
The various properties of a mail message are included as properties of the MailItem class: to, subject, body, and so forth.
The SaveSentMessageFolder property of the MailItem class allows you to designate where a copy of the message should be saved (it is optional).
The Send method of the MailItem class sends the message via Outlook.
Message creation is included in a try/catch block that handles COM exceptions. The COMException class is available in the System.Runtime.InteropServices namespace, so this namespace should be included in the code.

Outlook security

Security is an important aspect of Outlook, and allowing external code to create and send mail messages is considered a big security risk. When and if you execute the code in the previous example, you will see an Outlook security dialog box that says "A program is trying to automatically send e-mail on your behalf. Do you want to allow this? If this is unexpected, it may be a virus and you should choose 'No'." The dialog box contains Yes, No, and Help buttons, so the user may cancel the operation with a simple click of the mouse.

Creating an appointment

In the next example, we create an Outlook appointment to appear on the user's calendar. Once again, the base Application object is utilized. In addition, an AppointmentItem is used as opposed to the previously used MailItem since we are creating a calendar entry. Listing C uses C# to demonstrate how you may accomplish this. Listing D provides the example in VB.NET.

A few notes on the code:

The AppointmentItem class includes various properties for setting up an appointment. In this example, we utilize the Subject (what appears in the calendar), body (visible when an entry is opened), location, start date/time, and end date/time.
The ReminderSet property of the AppointmentItem class determines if a reminder is displayed to the user. The associated ReminderMinutesBeforeStart property determines when the reminder will be displayed.
The Importance property of the AppointmentItem class sets the item's importance. Values for the property are set via the OlImporantance enumerator, which has the following values: olImportanceHigh, olImportanceLow, and olImportanceNormal.
The BusyStatus property determines how the appointment is displayed on the calendar (i.e., whether the time is blocked off as busy, tentative, free, and so forth. The OlBusyStatus enumerator contains the following list of possible values: olBusy, olFree, olOutOfOffice, and olTentative.

Another developer option

Microsoft Office is the most popular office productivity suite in the world, and it is a desktop standard for most large organizations. For this reason, it is often available for you to take advantage of in your .NET applications. A Windows Forms application may easily utilize the mail features of Outlook and, likewise, add calendar appointments or contact database entries with very little code. The interoperability between the .NET platform and Microsoft Office greatly expand the developer's options.

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