mailer-patterns

Mailer Patterns

Philosophy: Minimal Mailers, Bundled Notifications

• Plain-text first, minimal HTML styling with inline CSS
• Bundle notifications instead of sending one email per event
• Transactional emails only (no marketing campaigns)
• deliver_later for individual emails; deliver_now is acceptable inside background jobs that already run asynchronously (e.g., digest delivery jobs)
• Email previews for development
• No email service abstraction layers (use Action Mailer directly)

Project Knowledge

Stack: Action Mailer (built-in), Solid Queue for background delivery, email previews in development, plain text + HTML multipart emails.

Multi-tenancy: Account-scoped emails, from address includes account context, unsubscribe links scoped to account.

Commands:

rails generate mailer Comment mentioned         # Generate mailer
rails generate mailer Digest daily_activity      # With methods
# Visit http://localhost:3000/rails/mailers      # Preview emails

Pattern 1: Simple Transactional Mailers

# app/mailers/application_mailer.rb
class ApplicationMailer < ActionMailer::Base
  default from: ENV.fetch("MAILER_FROM_ADDRESS", "Fizzy <[email protected]>")
  layout "mailer"
end

# app/mailers/comment_mailer.rb
class CommentMailer < ApplicationMailer
  def mentioned(mention)
    @mention = mention
    @comment = mention.comment
    @card = mention.comment.card
    @account = mention.account

    mail(
      to: mention.user.email,
      subject: "#{mention.creator.name} mentioned you in #{@card.title}"
    )
  end

  def new_comment(comment, recipient)
    @comment = comment
    @card = comment.card
    @account = comment.account

    mail(
      to: recipient.email,
      subject: "New comment on #{@card.title}"
    )
  end
end

# app/mailers/membership_mailer.rb
class MembershipMailer < ApplicationMailer
  def invitation(membership)
    @membership = membership
    @account = membership.account
    @inviter = membership.inviter

    mail(
      to: membership.user.email,
      subject: "#{@inviter.name} invited you to #{@account.name}"
    )
  end
end

# app/mailers/card_mailer.rb
class CardMailer < ApplicationMailer
  def assigned(assignment)
    @assignment = assignment
    @card = assignment.card
    @account = assignment.account

    mail(
      to: assignment.user.email,
      subject: "#{assignment.assigner.name} assigned you to #{@card.title}"
    )
  end
end