注意点：sendgrid的password如果被在github中公开，则sendgrid账号会被禁止使用

开发环境中使用gmail

#与controller的使用规则类似，在终端运行下面的代码
rails g mailer UserMailer

#在user_mailer.rb文件中建立如下的代码：
class UserMailer < ApplicationMailer
  default from: "[email protected]"

  def welcome_email
    mail(to: "[email protected]", subject: "Welcome to My Awesome Site")
  end
end

#建立两个视图文件，分别是welcome_email.html.erb文件和welcome_email.text.erb文件：

#进行文件配置，在config/environments/developments.rb中添加如下代码：

config.action_mailer.raise_delivery_errors = true
config.action_mailer.default_url_options = {host: "localhost:3000"}
config.action_mailer.delivery_method = :smtp                  
config.action_mailer.smtp_settings = {                                   
  address: "smtp.gmail.com",                                             
  port: 587,                                                             
  user_name: "zhengjiajun121",                                           
  password: "xxx",                                                 
  authentication: "plain",                                               
  enable_starttls_auto: true } 

#在终端执行下面的文件，邮件可以从gmail邮箱发送至foxmail邮箱中：
UserMailer.welcome_email.deliver_now

开发环境中使用sendgrid

#类似controller操作 rails g mailer notification_user
class ApplicationMailer < ActionMailer::Base
  default from: '[email protected]' #可以随意赋值
  layout 'mailer'
end
class NotificationUserMailer < ApplicationMailer
  def welcome
    mail to: "[email protected]", subject: "welcome the app"
  end
end

#config/environments/development.rb
config.action_mailer.default_url_options = { host: "localhost:3000" } #使得邮件中的链接地址有效
config.action_mailer.raise_delivery_errors = false
config.action_mailer.perform_caching = false

#config/initializers/sendgrid.rb
ActionMailer::Base.smtp_settings = {
  :user_name => 'apikey',
  #需要使用ENV['SENDGRID_API_KEY'],不然sendgrid的password被发布，账号会被禁止
  :password => 'password',
  :domain => 'zhengjiajun.com',
  :address => 'smtp.sendgrid.net',
  :port => 587,
  :authentication => :plain,
  :enable_starttls_auto => true
}

#在终端执行
NotificationUserMailer.welcome.deliver_now

生产环境中使用sendgrid

#类似controller操作 rails g mailer notification_user
class ApplicationMailer < ActionMailer::Base
  default from: '[email protected]' #可以随意赋值
  layout 'mailer'
end
class NotificationUserMailer < ApplicationMailer
  def welcome
    mail to: "[email protected]", subject: "welcome the app"
  end
end

#config/environments/development.rb
config.action_mailer.default_url_options = { host: "zhengjiajun.com } #使得邮件中的链接地址有效
config.action_mailer.raise_delivery_errors = false
config.action_mailer.perform_caching = false

#config/initializers/sendgrid.rb
ActionMailer::Base.smtp_settings = {
  :user_name => 'apikey',
  #需要使用ENV['SENDGRID_API_KEY'],不然sendgrid的password被发布，账号会被禁止
  :password => 'password',
  :domain => 'zhengjiajun.com',
  :address => 'smtp.sendgrid.net',
  :port => 587,
  :authentication => :plain,
  :enable_starttls_auto => true
}

#在终端执行
NotificationUserMailer.welcome.deliver_now