I got two variants that slipped past my filters overnight:Yahoo! groups
email@example.com has invited you to join Build_Instant_Money_Now on Yahoo! Groups, the best way to discover and share information and advice with others.Google Calendar
Description: Dear Good Friend,
I am very happy to inform you about my success in getting those funds transferred under the cooperation of a new partner in London,Presently,I'm in saudi arabia for the purpose of investing my own share of the money.
An interesting way to deliver spam. It reminds me a bit of a key weakness of DJB's IM2000, where the message availability notifications can be used to carry spam payloads regardless of their intended purpose.