About configuring constants
To display static text for all email in a mailing, you can define a constant in the mailing configuration. If you define a constant in the mailing configuration, the document referenced by the mailing must contain the corresponding constant personalization field. A mailing can define multiple constants if the referenced document contains the required constant personalization fields.
When you configure the constant on the mailing tab, you are specifying the text that the constant personalization field displays in the message. The text that you enter appears only for the mailing you are configuring and appears in the same way in every message sent as part of the mailing.
Because you create constant personalization fields at the Deliver installation level, you can use the same constant personalization field in multiple mailings. However, you configure the text displayed by a constant personalization field at the mailing level. Because you configure the field's text value as part of the mailing configuration, the same constant personalization field can display different text in various mailings.
For more information about defining and managing constant personalization fields, see Constant personalization fields.