Chatwoot/app/mailers/application_mailer.rb

class ApplicationMailer < ActionMailer::Base
  default from: ENV.fetch('MAILER_SENDER_EMAIL', 'accounts@chatwoot.com')
  layout 'mailer'

  # helpers
  helper :frontend_urls

  def smtp_config_set_or_development?
    ENV.fetch('SMTP_ADDRESS', nil).present? || Rails.env.development?
  end
end