Cargo Features

email_address = { version = "0.2.4", default-features = false, features = ["serde_support"] }
default = serde_support

The serde_support feature is set by default whenever email_address is added without default-features = false somewhere in the dependency tree.

serde_support default = serde

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.

serde serde_support