Gateway for the optional gen_smtp dependency ({:gen_smtp, "~> 1.3"}).

Used for SMTP relay ingress in mailglass_inbound (v0.5+). Not needed by mailglass core for outbound — Swoosh handles SMTP transport via its own Swoosh.Adapters.SMTP which declares :gen_smtp as its own optional dep.

The :gen_smtp Hex package is an Erlang library; the entry module is the erlang atom :gen_smtp_client. There is no GenSmtp Elixir module. Code.ensure_loaded?/1 accepts Erlang module atoms transparently.