Cargo Features

AMQP has no features set by default.

[dependencies]
amqp = { version = "0.1.3", features = ["tls"] }
tls = openssl

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.

openssl tls?

Enables openssl 0.7.*