To create a new message:

Choose Message > New Message.

Use the From pop-up menu to choose the sender of this message. This will be the "From:" address shown in the message's header.

Enter a subject for the message.
One Direct Mail document can contain multiple messages. By default, a new message is created whenever you open a new document.
Choose Message > New Message.
Use the From pop-up menu to choose the sender of this message. This will be the "From:" address shown in the message's header.
Enter a subject for the message.