Bamboo is a mature, well-architected Elixir library for composing and delivering emails through adapters. It provides a clean functional API for building email structs, a powerful address normalization system via the `Bamboo.Formatter` protocol, and built-in adapters for Mailgun, Mandrill, SendGrid, local in-memory storage, and testing. The library supports background delivery, email interceptors, attachments, plug-based preview of sent emails, and comprehensive test helpers. Production code is separated from optional Phoenix view integration (extracted to bamboo_phoenix). The architecture uses behaviours for adapters and delivery strategies, making it extensible. It is actively maintained, with recent commits and CI passing on Elixir 1.17-1.19.