Action Mailer setup in Ruby on Rails - Step-by-Step Execution

Concept Flow - Action Mailer setup

Create Mailer Class

↓

Define Mail Method

↓

Configure SMTP Settings

↓

Call Mail Method

↓

Generate Email

↓

Send Email via SMTP

↓

Done

This flow shows how to set up Action Mailer: create a mailer, define email methods, configure SMTP, call the mail method, generate the email, and send it.

Execution Sample

Ruby on Rails

class UserMailer < ApplicationMailer
  def welcome_email(user)
    @user = user
    mail(to: @user.email, subject: 'Welcome!')
  end
end

Defines a mailer class with a method to send a welcome email to a user.

Execution Table

Step	Action	Details	Result
1	Create Mailer Class	UserMailer inherits from ApplicationMailer	Mailer class ready
2	Define Mail Method	welcome_email(user) sets @user and mail params	Method ready to send email
3	Configure SMTP	Set SMTP settings in config/environments/*.rb	Mailer can send emails via SMTP
4	Call Mail Method	UserMailer.welcome_email(user).deliver_now	Email object created and sent
5	Generate Email	Prepare email body and headers	Email content ready
6	Send Email via SMTP	SMTP server sends email to recipient	Email delivered
7	End	Process complete	Email sent successfully

💡 Email sent successfully after SMTP delivery

Variable Tracker

Variable	Start	After Step 2	After Step 4	Final
@user	nil	User object assigned	User object assigned	User object assigned
mail object	nil	nil	Created with to and subject	Sent via SMTP

Key Moments - 3 Insights

Why do we need to configure SMTP settings separately?

SMTP settings tell Rails how to send emails through a mail server. Without this, emails can't be delivered. See step 3 in execution_table.

What does the mail() method do inside the mailer?

The mail() method sets the email headers like recipient and subject, and prepares the email to be sent. Refer to step 2 and 4 in execution_table.

Why call deliver_now after mailer method?

Calling deliver_now actually sends the email immediately. Without it, the email is just prepared but not sent. See step 4 in execution_table.

Visual Quiz - 3 Questions

Look at the execution_table, at which step is the email content prepared?

A Step 5: Generate Email

B Step 2: Define Mail Method

C Step 4: Call Mail Method

D Step 6: Send Email via SMTP

💡 Hint

Check the 'Details' column for when email body and headers are prepared.

According to variable_tracker, what is the state of the mail object after step 4?

A nil

B Created with to and subject

C Sent via SMTP

D User object assigned

💡 Hint

Look at the 'mail object' row under 'After Step 4' column.

If SMTP settings are missing, which step in execution_table would fail?

A Step 2: Define Mail Method

B Step 3: Configure SMTP

C Step 6: Send Email via SMTP

D Step 5: Generate Email

💡 Hint

Sending email requires SMTP; see step 6 description.

Concept Snapshot

Action Mailer setup:
- Create mailer class inheriting ApplicationMailer
- Define mail methods with mail(to:, subject:)
- Configure SMTP in environment files
- Call mailer method with deliver_now to send
- Email is generated then sent via SMTP
- SMTP config is essential for delivery

Full Transcript

Action Mailer setup in Rails involves creating a mailer class that inherits from ApplicationMailer. Inside, you define methods that prepare emails using the mail() method with recipient and subject. You must configure SMTP settings in your environment files so Rails knows how to send emails through a mail server. When you call the mailer method with deliver_now, Rails generates the email content and sends it immediately via SMTP. Without SMTP configuration, sending will fail. This flow ensures emails are prepared and delivered correctly.