Security Advisory: removed deprecated lettre_email from the dependencies that had the `[email protected]` dependency that could potentially cause segfaults. See: https://rustsec.org/advisories/RUSTSEC-2020-0071 Users are highly advised to update dead-man-switch crates/binaries to the newest 0.6.0 tag. All previous 0.5.X versions are yanked from crates.io.