lettre 0.10.0-rc.1

Email client
Documentation
## Report a security issue

The lettre project team welcomes security reports and is committed to providing prompt attention to security issues.
Security issues should be reported privately via [security@lettre.rs](mailto:security@lettre.rs). Security issues
should not be reported via the public Github Issue tracker.

## Security advisories

Security issues will be announced via the [RustSec advisory database](https://github.com/RustSec/advisory-db).