correct_single_responsibility_principle.rb

class ReportSender
  def initialize(report, account)
    @report = report
    @account = account
  end

  def send_report
    Mailer.deliver(
      from: 'foo@bar.com',
      to: @account.email,
      subject: 'Report',
      body: @report
    )
  end
end

class ReportGenerator
  def initialize(data)
    @data = data
  end

  def generate
    @data.map { |row| "User: #{row.user} action: #{row.action} date: #{row.created_at}"
    }.join("\n")
  end
end

report = ReportGenerator.new(data).generate
ReportSender.new(report, account).send_report