Originally discovered by a community member http://www.liferay.com/community/forums/-/message_boards/message/5398219
1) Add Message Boards portlet
2) create a board on message boards
3) Add category and under "Mailing List" check "Active"
4) Create a gmail account or other imap mail account
6) In the email account, send 2 emails to yourself. Make 1 read, 1 unread.
5) Add it to the Mailing List thing using the IMAP credentials
7) Wait a bit and your email will go from the inbox to the sent folder.