test: add tests for Server model

config/initializers/smtp.rb

@@ -3,6 +3,8 @@
 require "postal/config"
 
 if Postal.config&.smtp
+  # TODO: by default, we should just send mail through the local Postal
+  # installation rather than having to actually configure an SMTP server.
   ActionMailer::Base.delivery_method = :smtp
   ActionMailer::Base.smtp_settings = { address: Postal.config.smtp.host, user_name: Postal.config.smtp.username, password: Postal.config.smtp.password, port: Postal.config.smtp.port || 25 }
 end