Today, we committed a big change into VMime codebase. We implemented preliminary support for RFC-6532 (Internationalized Email Headers), which is the (future) replacement for RFC-2047. We added support for IDN (Internationalized Domain Name) and EAI (Email Address Internationalization).
As a lot of MUAs and MSAs do not support this yet, the feature is not enabled by default (and, to be honest, we need to test this thoroughly in VMime before using it in production code). To enable it from your code, just configure the default generation context:
In the meantime, we also added message generation/parsing context and charset conversion options, to provide a better control to the user on how the messages are parsed/generated. Have a look at Doxygen-generated documentation to know more about this.