Cargo Features
pop3-client has no features set by default.
[dependencies]
pop3-client = { version = "0.2.1", features = ["with-rustls"] }- with-rustls = rustls, webpki, webpki-roots
Features from optional dependencies
In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features. These features may have been created by mistake, and this functionality may be removed in the future.