A functioning Swoosh SMTP config

Spent about 3 hours fiddling around with different configurations of Swoosh, Elixir's most popular email library. Documentation is sparse, but this Elixir forum post got me to the answer. For reference, I'm using this with Purelymail, but it should be generic enough to use with any email provider that uses SSL.

config :your_app, YourApp.Mailer,
    adapter: Swoosh.Adapters.SMTP,
    relay: System.get_env("SMTP_SERVER"),
    username: System.get_env("SMTP_EMAIL"),
    password: System.get_env("SMTP_PASSWORD"),
    port: 465,
    ssl: true,
    tls: :never,
    auth: :always,
    retries: 2,
    no_mx_lookups: false,
    sockopts: [
      versions: [:"tlsv1.2", :"tlsv1.3"],
      verify: :verify_peer,
      cacerts: :public_key.cacerts_get(),
      depth: 3,
      customize_hostname_check: [
        match_fun: :public_key.pkix_verify_hostname_match_fun(:https)
      ],
      server_name_indication: ~c"your-email-server-here.com"
    ]

If the provider uses STARTTLS instead of SSL, I think you would remove the ssl: true line and make tls: :always instead of :never.