Get a GMail account for yourself and your accountant; choose half-decent secret questions; enable two-factor authentication; use webmail (exclusively) to send m

Get a GMail account for yourself and your accountant; choose half-decent secret questions; enable two-factor authentication; use webmail (exclusively) to send mail back and forth. (Do not set GMail to forward mail to another account.) It should be obvious that this isn't secure if your local government decides to come after you, and will likely fail if someone specifically comes after you(r accountant), but it does keep mail from travelling over unprotected lines and stored on a pretty well-protected system. Crucially, although it's slightly less secure than a perfect implementation of some of the other suggestions on this page, it's much easier. [GMail is good, but not magical; if your accountant already has an account at, say, Hotmail, consider setting up a Hotmail account instead, even if you do lose two-factor authentication in the process.]