Using Outlook Help for Sharing Distribution List:
Share a distribution list with others
You can send a distribution list to others by including it in a message. The recipient can then save it to their Contacts.
To send a distribution list:
Open a new message. Open Contacts. Drag the distribution list from Contacts into the message body.
Note You may need to adjust the message and the Contacts window so that they're visible at the same time.
When I try this method of dragging the distribution list into a new mail message, the distribution list pops into the attachment line. What am I doing wrong?