or individually revocable inbox post URL. Thoughtmail might circumvent this by storing your apikey in the email address strongly encrypted.
not sure how to handle images without hosting outside of thoughtstreams.
would like auto linking of urls in addition to markdown syntax. [will prototype in Thoughtmail]
skip inbox and post directly to streams. Thoughtmail could use a list of stream names in the subject. Drafts lets you configure it's email sending to have a preset subject so you can add email actions for specific streams.
some mechanism for publishing a card from the API.