Yet a "safe" email system is now gone. A better idea would be to move yourself and your encrypted email company to a country that will let you keep providing such a useful service (assuming there is one).
Email is not safe, by design. Even if you do encrypt the contents using PGP or GPG, the headers are too much exposure. They will know who when and with whom you correspond, and all the hosts the mail passed through (if you are not using anonymous re-mailers). The current implementation of email is "defective by design". But _there_are_ alternatives [1], you must just start using them.
[1] RetroShare, BitMessage, I2P Bote, Freenet + Frost and some others, which haven't tried yet.
It might sound odd, but I think an easier solution is to commit to being persecuted by the tyranny. The alternatives are to prevent it or live under it, committing to the persecution should encourage prevention.
With NZ becoming less safe, it seems that's exactly what Mega intends to do for its storage service and the upcoming secure e-mail service. If he does it right, it could fill the space left Lavabit and Silent Mail.