Attaching documents
You have several opportunities to attach a document to an e-mail.
Documents from context
If you opened the e-mail distribution GUI via an object, you can use the label "Add existing document". If you click this label, you open a sheet. From this sheet you can choose documents, which are attached to the object.
Documents from local file system
Click on the label "Add local file" to open a dialog. From this dialog you can choose a local file. Alternatively you can add several files via Drag'n'Drop.