SMTP: lettre crate in Rust

Have anyone done with the last version(0.9.2) with lettre crate, because in my practice book it's use v0.7 so it's different in the point of trait. In v0.7 lettre::SendableEmail in Trait but in in v.0.9.2 lettre::SendableEmail in struct. And I want to impl Trait. If anyone have done with this please share. Thank you very much.