Mailer class name without Mailer suffix RB-C1018

Classes implementing mailing functionality (inheriting from ActionMailer::Base or ApplicationMailer) should be named with a Mailer suffix.

Suffixing Mailer to the class name ensures there is no confusion about the responsibilities of the class, as classes like User are conventionally used for ActiveRecord Models.

Bad practice

class User < ActionMailer::Base
end

class User < ApplicationMailer
end

Recommended

class UserMailer < ActionMailer::Base
end

class UserMailer < ApplicationMailer
end