1-- subject_reminder.lua
 2-- Warns you if you're composing an email without a subject line.
 3
 4local matcha = require("matcha")
 5
 6matcha.on("email_send_before", function(email)
 7    if email.subject == "" then
 8        matcha.notify("Warning: no subject line!", 3)
 9    end
10end)