What is the indirect object in following sentence Trevor sent his mother postcard?

The indirect object in the sentence "Trevor sent his mother a postcard" is his mother.

Here's why:

* Direct Object: The direct object is the thing that receives the action of the verb. In this case, the postcard is the direct object because Trevor is sending it.

* Indirect Object: The indirect object is the person or thing that is indirectly affected by the action of the verb. It usually answers the question "to whom?" or "for whom?" Trevor is sending the postcard *to his mother*.