And if that is a concern, then it’s the appropriate time to use a disposable e-mail account, Tor, and a pseudonymous PGP key (arranged out-of-band, especially in-person). It still amounts to this bizarre, unfounded assumption that a protocol which does not require encryption and does not have anonymity built-in to the spec is somehow secure, for some definition of secure.
And yes, snooping on e-mail is bad. But it’s really most appropriate to have been assuming that someone has been (or at the very least could have been) reading your e-mail (or headers) all along, given how the protocol works.
