mozilla Disable official Thunderbird branding (icons, name) which are not binary-redistributable according to upstream. Enable encryption support with enigmail Enable Mozilla's DOM inspector Enable calendar support Fine-tune custom compiler optimizations (-Os, -O0, -O1, -O2, -O3) Use the system-wide x11-libs/cairo instead of bundled. Use the system-wide dev-libs/icu instead of bundled. Use the system-wide media-libs/libjpeg-turbo instead of bundled. Use the system-wide media-libs/libvpx instead of bundled. Use the system-wide dev-db/sqlite installation with secure-delete enabled Remove the software development kit and headers