サインアップ(devise)した時に、登録したメールアドレスにメッセージを送られるようにしたいが、登録時に止まってしまい、送ることができない状態にいます。
もしわかる方がいらしたら、教えて頂きたいです。

問題：登録を押した際に起きたエラー(上の動作の後に)

Completed 500 Internal Server Error in 845ms (ActiveRecord: 52.6ms)

Net::SMTPFatalError (555 5.5.2 Syntax error. p136sm891772lfp.86 - gsmtp
):
  app/models/tourist.rb:13:in `send_welcome_mail'

Terminal結果

TouristMailer#tourist_welcome_mail: processed outbound mail in 47.6ms

Sent mail to <@tourist.email> (545.9ms)
Date: Sat, 04 May 2019 14:28:54 +0300
From: chancetochance2018@gmail.com
To: <@tourist.email>
Message-ID: <5ccd7776e7305_ab733fbfc403e49010004a@ishiwatadohiroshi-no-MacBook-Air.local.mail>
Subject: =?UTF-8?Q?=E3=81=8A=E5=95=8F=E3=81=84=E5=90=88=E3=82=8F=E3=81=9B?=
Mime-Version: 1.0
Content-Type: multipart/alternative;
 boundary="--==_mimepart_5ccd7776e1b11_ab733fbfc403e49099912";
 charset=UTF-8
Content-Transfer-Encoding: 7bit


----==_mimepart_5ccd7776e1b11_ab733fbfc403e49099912
Content-Type: text/plain;
 charset=UTF-8
Content-Transfer-Encoding: base64

SGlybyDmp5jjgYvjgonllY/jgYTlkIjjgo/jgZvjgYzjgYLjgorjgb7jgZfj
gZ/jgIINCg0K44O744GK5ZWP44GE5ZCI44KP44GbDQoNCg0K

----==_mimepart_5ccd7776e1b11_ab733fbfc403e49099912
Content-Type: text/html;
 charset=UTF-8
Content-Transfer-Encoding: quoted-printable

<html>=0D
  <body>=0D
    <!doctype html>=0D
<html lang=3D"ja">=0D
<head>=0D
  <meta content=3D"text/html; charset=3DUTF-8" />=0D
</head>=0D
<body>=0D
  <h2>Hiro =E6=A7=98</h2>=0D
  <hr />=0D
  <p>=0D
    =E3=81=93=E3=82=93=E3=81=AB=E3=81=A1=E3=81=AF=EF=BC=81 Hiro=E3=81=95=E3=
=82=93=EF=BC=81</p>=0D
  <hr />=0D
</body>=0D
</html>=0D
=0D
  </body>=0D
</html>=0D

----==_mimepart_5ccd7776e1b11_ab733fbfc403e49099912--

   (9.5ms)  ROLLBACK

Completed 500 Internal Server Error in 845ms (ActiveRecord: 52.6ms)

Net::SMTPFatalError (555 5.5.2 Syntax error. p136sm891772lfp.86 - gsmtp):
app/models/tourist.rb:13:in `send_welcome_mail'

実際のコード

views/tourist_welcome_mailer.html.erb

<!doctype html>
<html lang="ja">
<head>
  <meta content="text/html; charset=UTF-8" />
</head>
<body>
  <h2><%= @tourist.name %> 様</h2>
  <hr />
  <p>
    こんにちは！ <%= @tourist.name %>さん！</p>
  <hr />
</body>
</html>

mailers/tourist_mailer.rb

class TouristMailer < ApplicationMailer
    default from: '<chancetochance2018@gmail.com>'

    def tourist_welcome_mail(tourist)
      @tourist = tourist
      mail(
        from: '<chancetochance2018@gmail.com>',
        to:    '<'+'@tourist.email'+'>',
        subject: 'お問い合わせ'
        )
    end
 end

model/tourist.rb

after_create :send_welcome_mail

def send_welcome_mail
  TouristMailer.tourist_welcome_mail(self).deliver_now
end

config/development.rb

  config.consider_all_requests_local       = true
  config.action_controller.perform_caching = false
  config.action_mailer.delivery_method = :smtp
  config.action_mailer.smtp_settings = {
    address:              'smtp.gmail.com',
    port:                  587,
    domain:               'smtp.gmail.com',
    user_name:            'chancetochance2018@gmail.com',
    password:             '???????????',
    authentication:       'plain',
    enable_starttls_auto:  true
  }