Attachments

You can attach any file of any type to the message. List of attachments is available in the upper part of the new message dialog. (The new message dialog is divided into several folds, attachments are the second one)

Attaching

You can attach new attachment using

button attach file next to the list of attachments
command attach file available from menu attachments
directly by dragging the file by mouse over the new message dialog

You can attach multiple files at the same time.

Detaching

You can detach selected attachment by clicking the detach file button next to the list of attachments.