expression.EmailTemplate
expression Required. An expression that returns an Application object.
Remarks
Use the EmailTemplate property when Microsoft Word is specified as your e-mail editor, which you must do inside Microsoft Outlook.
Example
This example instructs Word to use the template named "Email" for all new e-mail messages. This example assumes that you have a template named "Email" and that it is stored in the default template location.
Sub MessageTemplate()
Application.EmailTemplate = "Email"
End Sub