Python API for Dropbox

Here is a brief sample with the functionality that you want:

import sys
import dropbox

print 'Running'

dbx = dropbox.Dropbox('<GENERATED ACCESS TOKEN FROM MY APPS PAGE>')
curr_account = dbx.users_get_current_account()

shared_folder_name = '<SHARED FOLDER NAME>'

# Create a shared folder
launch = dbx.sharing_share_folder('/' + shared_folder_name)

if not launch.is_complete():
 print 'Shared folder creation failed, exiting'
 sys.exit(-1)

meta_data = launch.get_complete()
member_select = dropbox.sharing.MemberSelector.email('<INVITEE EMAIL>')
access_level = dropbox.sharing.AccessLevel.editor
add_member = dropbox.sharing.AddMember(member_select, access_level)

dbx.sharing_add_folder_member(meta_data.shared_folder_id, [add_member], 
 custom_message="<CUSTOM EMAIL MESSAGE>")