[cstross]

Alternatively, power users can just go back to mutt: http://www.mutt.org/

Unless I'm reading this wrong, the service relies on the broken misfeature of many modern email clients that diverge from the original RFCs for mail by treating HTML as something they can process. A client that only handles plain text email (with attachments as something separate to hand off to an external program) is safe from this kind of abuse.