Attach a file or a folder to a message
You can send files and folders by attaching them to an e-mail message. When you attach a folder, Outlook compresses the contents of the folder into a single .zip file.
In your message, on the Message tab, click Attach.
Locate the item or folder that you want to attach, select it, and then click Choose.
If you are attaching a folder, on the confirmation dialog box, click Compress.