Rails not sending email on development

Question

I am developing an app on Rails 4. When user signs up using devise gem, that person can receive an email. But for cases like successful checkout, the user not getting any email despite there is InvoiceMailer#checkout: processed outbound mail in 207.2ms and Sent mail to admin@example.com (4134.8ms) message in console.

Following were my code: Controller

def success_checkout

        token = params[:token]
        payer_id = params[:PayerID]
        @invoice = Invoice.find_by_token(token)

        request = Paypal::Express::Request.new(
            :username   => PAYPAL_CONFIG[:username],
            :password   => PAYPAL_CONFIG[:password],
            :signature  => PAYPAL_CONFIG[:signature]
        )

        payment_request = Paypal::Payment::Request.new(
            :currency_code => @invoice.currency,   
            :description   => "New payment for travel booking",
            :quantity      => 1,
            :amount        => @invoice.amount_cents.to_i / 100
        )

        response = request.checkout!(
            params[:token],
            params[:PayerID],
            payment_request
        )

        gon.is_display_currency_exchange = false
        @currency_symbol = get_all_currency_symbols[@invoice.currency]

        if response.ack == 'Success'
            @invoice.update_attributes(:payer_id => payer_id, :status => "paid")

            if @invoice.is_reward_credit
                current_user.reward_credit -= 5
                current_user.save
            end

            (1..3).each do |i|
                InvoiceMailer.checkout(@invoice, i).deliver_now
            end

            flash[:success] = "Checkouted successfully."
        else
            flash[:danger] = "There is an error while processing the payment."
        end

    end 

InvoiceMailer

class InvoiceMailer < ActionMailer::Base
    default from: "MySite <support@example.com>"
    include ApplicationHelper

    def checkout(invoice,i)
        @invoice = invoice
        @currency_symbols = get_all_currency_symbols


        logger.info "{event=CHECKOUT_RECEIPT status=successful store=#{invoice.contact_detail.email}}"  
        mail(:to => invoice.contact_detail.email, :subject => "Receipt of example")



    end

end

My development.rb mailer config

#For mailer configs
config.action_mailer.delivery_method = :smtp
config.action_mailer.perform_deliveries = true
config.action_mailer.default_url_options = { host: 'www.example.com'};
config.action_mailer.smtp_settings = {
    :address        => 'email-smtp.us-west-2.amazonaws.com',
    :port => 587,
    :authentication => :plain,
    :user_name      => 'KEY',
    :password       => 'SECRET',
    :enable_starttls_auto => true
}

The logger message do print out in console as {event=CHECKOUT_RECEIPT status=successful store=user@example.com}. But receive no mail. Thanks!!!