Office 386 (Outlook 2013 / 2016 for Win) - Open or Save an Email Message Attachment
You can open an attachment from the Reading Pane or from an open message. After opening and viewing an attachment, you can save it. If a message has more than one attachment, you can save them as a group or one at a time.
Open an attachment:
Double-click the attachment.
Save an attachment:
1. Click the attachment in the Reading Pane or the open message.
2. On the Attachments tab, in the Actions group, click Save As. You can also right-click the attachment, and then click Save As.