Form Name and Message Class Overview
The message class is an internal identifier used by Microsoft Office Outlook and Microsoft Exchange to locate and activate a form .
The message class property corresponds to the MAPI property PR_MESSAGE_CLASS. This class property determines which receiving folder the message should be routed to and which form should be activated to view the message.
Creating a message class when customizing form regions
Form regions give you more control over how Outlook handles your customized form. Depending on the type of form region that you use when customizing a form, you need to create a unique message class for your form. Learn more about creating a message class for a form region in How to: Create a Form Region.
Creating a message class when customizing form pages
In the Publish Form As dialog box, when you type a name in the Display name field, you will notice that the Form name field reflects the display name by default. You can leave the form name to be the same as the display name or you can change the form name. The display name will be the caption at the top of your form. The display name will also be used to construct the name under which your form will be published. When you publish your form, the display name will be listed in the Choose Form dialog box.
Outlook automatically constructs a message class for the form by preceding the form name with IPM. For instance, if you publish a mail message form that you want to name "MyForm", in the Display name field, type: This is my Form. In the Form name field, type: MyForm. At the bottom of the dialog box, Outlook will display the message class for your new form as: IPM.Note.MyForm.
When you search in the Choose Form dialog box, you will see "This is my Form" displayed in the list. If you select it, the Display name field at the bottom of the dialog box will display, "This is my Form" and the Form name field will display, "MyForm".
A message class, which is generated automatically by Outlook from the form name, is assigned to the form. When a form with that message class is selected, Outlook loads and displays an instance of that form. Outlook will use the message class, IPM.Note.MyForm, to locate the form with the display name, "This is my Form".