Currently there is no support for this in MTA software. If it were supported, you could imagine having somewhat better privacy properties for e-mail with other

Currently there is no support for this in MTA software. If it were supported, you could imagine having somewhat better privacy properties for e-mail with other people who also used this particular setup. However, if you simply re-decentralize your e-mail using today's e-mail technology, you won't get those benefits in the short term.