A simle mail sending API (one route) to send email message by using the ruby mail gem (already configured for sending via gmail). This API is meant to be used to back a JS contact form, but feel free to modify to send any kind of messages (alert, logs, etc...).
bundle exec rackup
POST /mail from_name: "Mario Foo" from_address: "firstname.lastname@example.org", body: "bar"
easy as that,