Devise, Sendgrid
config/initializers/devise.rb :
config.mailer_sender = "mail-to-send@from.com"
config/environments/production.rb :
config.action_mailer.default_url_options = { :host => 'your.websitedomain.com' }
ActionMailer::Base.smtp_settings = {
:address => "smtp.sendgrid.net",
:port => "25",
:authentication => :plain,
:user_name => ENV['SENDGRID_USERNAME'],
:password => ENV['SENDGRID_PASSWORD'],
:domain => ENV['SENDGRID_DOMAIN']
}