FormNameRuleCondition.FormName Property (Outlook)
Returns or sets an Object that represents an array of form identifiers to be evaluated by the rule condition. Read/write.
Even though the Rules and Alerts Wizard uses the display name of a form as an identifier, programmatically, FormName uses the message class of the form as an identifier.
You can assign an array with one string or an array of multiple strings to the FormName property. Multiple form identifiers assigned in an array are evaluated using the logical OR operation.
FormName returns an error if it contains one or more empty strings.