本番環境(Heroku)でメールを送信できません。

前提・実現したいこと

Rails Tutorialの１１章にてメールの有効化をしたのですが、本番環境(Heroku)で、新規登録すると「We're sorry,but something went wrong」と出ます。
開発環境では動くのですが、本番環境になると動きません。

Herokuのログ

日付は文字数削減のため、nowとしました。

now.939193+00:00 app[web.1]: D, [now.938588 #9] DEBUG -- : [52c2ba12-f1fb-43ff-b988-79e7e3acb43b]    (3.9ms)  COMMIT
now.944183+00:00 app[web.1]: I, [now.944078 #9]  INFO -- : [52c2ba12-f1fb-43ff-b988-79e7e3acb43b]   Rendering user_mailer/account_activation.html.erb within layouts/mailer
now.949736+00:00 app[web.1]: I, [now.946975 #9]  INFO -- : [52c2ba12-f1fb-43ff-b988-79e7e3acb43b]   Rendered user_mailer/account_activation.html.erb within layouts/mailer (Duration: 0.5ms | Allocations: 79)
now.950433+00:00 app[web.1]: I, [now.950357 #9]  INFO -- : [52c2ba12-f1fb-43ff-b988-79e7e3acb43b]   Rendering user_mailer/account_activation.text.erb within layouts/mailer
now.957289+00:00 app[web.1]: I, [now.957167 #9]  INFO -- : [52c2ba12-f1fb-43ff-b988-79e7e3acb43b]   Rendered user_mailer/account_activation.text.erb within layouts/mailer (Duration: 0.4ms | Allocations: 57)
now.960807+00:00 app[web.1]: D, [now.960710 #9] DEBUG -- : [52c2ba12-f1fb-43ff-b988-79e7e3acb43b] UserMailer#account_activation: processed outbound mail in 19.6ms
now.269757+00:00 app[web.1]: I, [now.269593 #9]  INFO -- : [52c2ba12-f1fb-43ff-b988-79e7e3acb43b] Delivered mail 6086752aecd8e_92ad8bac16c28920b2@f2443102-7906-452b-8f99-6d5f551f2edc.mail (301.4ms)
now.269856+00:00 app[web.1]: D, [now.269735 #9] DEBUG -- : [52c2ba12-f1fb-43ff-b988-79e7e3acb43b] Date: Mon, 26 Apr 2021 08:09:14 +0000
now.269857+00:00 app[web.1]: From: noreply@example.com
now.269858+00:00 app[web.1]: To: rorizeya@via.tokyo.jp
now.269858+00:00 app[web.1]: Message-ID: <6086752aecd8e_92ad8bac16c28920b2@f2443102-7906-452b-8f99-6d5f551f2edc.mail>
now.269859+00:00 app[web.1]: Subject: Account activation
now.269859+00:00 app[web.1]: Mime-Version: 1.0
now.269860+00:00 app[web.1]: Content-Type: multipart/alternative;
now.269861+00:00 app[web.1]: boundary="--==_mimepart_6086752ae9f6e_92ad8bac16c2891973";
now.269862+00:00 app[web.1]: charset=UTF-8
now.269862+00:00 app[web.1]: Content-Transfer-Encoding: 7bit
now.269863+00:00 app[web.1]: 
now.269863+00:00 app[web.1]: 
now.269863+00:00 app[web.1]: ----==_mimepart_6086752ae9f6e_92ad8bac16c2891973
now.269864+00:00 app[web.1]: Content-Type: text/plain;
now.269864+00:00 app[web.1]: charset=UTF-8
now.269865+00:00 app[web.1]: Content-Transfer-Encoding: quoted-printable
now.269865+00:00 app[web.1]: 
now.269865+00:00 app[web.1]: Hi =E3=81=A3=E3=81=A3g,=0D
now.269866+00:00 app[web.1]: =0D
now.269867+00:00 app[web.1]: Welcome to the Sample App! Click on the link below to activate your accou=
now.269867+00:00 app[web.1]: nt:=0D
now.269867+00:00 app[web.1]: =0D
now.269867+00:00 app[web.1]: https://stark-beyond-04633.herokuapp.com/account_activations/15Q7aXLXaDu6=
now.269868+00:00 app[web.1]: wWS1u8JDHA/edit?email=3Drorizeya%40via.tokyo.jp=0D
now.269868+00:00 app[web.1]: 
now.269869+00:00 app[web.1]: ----==_mimepart_6086752ae9f6e_92ad8bac16c2891973
now.269869+00:00 app[web.1]: Content-Type: text/html;
now.269869+00:00 app[web.1]: charset=UTF-8
now.269870+00:00 app[web.1]: Content-Transfer-Encoding: quoted-printable
now.269870+00:00 app[web.1]: 
now.269870+00:00 app[web.1]: <!DOCTYPE html>=0D
now.269871+00:00 app[web.1]: <html>=0D
now.269871+00:00 app[web.1]: <head>=0D
now.269871+00:00 app[web.1]: <meta http-equiv=3D"Content-Type" content=3D"text/html; charset=3Dutf=
now.269872+00:00 app[web.1]: -8" />=0D
now.269872+00:00 app[web.1]: <style>=0D
now.269873+00:00 app[web.1]: /* Email styles need to be inline */=0D
now.269873+00:00 app[web.1]: </style>=0D
now.269873+00:00 app[web.1]: </head>=0D
now.269874+00:00 app[web.1]: =0D
now.269874+00:00 app[web.1]: <body>=0D
now.269874+00:00 app[web.1]: <h1>Sample App</h1>=0D
now.269874+00:00 app[web.1]: =0D
now.269875+00:00 app[web.1]: <p>Hi =E3=81=A3=E3=81=A3g,</p>=0D
now.269875+00:00 app[web.1]: =0D
now.269875+00:00 app[web.1]: <p>=0D
now.269876+00:00 app[web.1]: Welcome to the Sample App! Click on the link below to activate your accou=
now.269876+00:00 app[web.1]: nt:=0D
now.269877+00:00 app[web.1]: </p>=0D
now.269877+00:00 app[web.1]: =0D
now.269877+00:00 app[web.1]: <a href=3D"https://stark-beyond-04633.herokuapp.com/account_activations/1=
now.269878+00:00 app[web.1]: 5Q7aXLXaDu6wWS1u8JDHA/edit?email=3Drorizeya%40via.tokyo.jp">Activate</a>=0D=
now.269878+00:00 app[web.1]: 
now.269878+00:00 app[web.1]: </body>=0D
now.269878+00:00 app[web.1]: </html>=0D
now.269879+00:00 app[web.1]: 
now.269879+00:00 app[web.1]: ----==_mimepart_6086752ae9f6e_92ad8bac16c2891973--
now.269879+00:00 app[web.1]: 
now.270220+00:00 app[web.1]: I, [now.270120 #9]  INFO -- : [52c2ba12-f1fb-43ff-b988-79e7e3acb43b] Completed 500 Internal Server Error in 1503ms (ActiveRecord: 25.9ms | Allocations: 6285)
now.271435+00:00 app[web.1]: F, [now.271340 #9] FATAL -- : [52c2ba12-f1fb-43ff-b988-79e7e3acb43b]
now.271436+00:00 app[web.1]: [52c2ba12-f1fb-43ff-b988-79e7e3acb43b] Net::SMTPFatalError (550 Unauthenticated senders not allowed
now.271436+00:00 app[web.1]: ):
now.271437+00:00 app[web.1]: [52c2ba12-f1fb-43ff-b988-79e7e3acb43b]
now.271438+00:00 app[web.1]: [52c2ba12-f1fb-43ff-b988-79e7e3acb43b] app/models/user.rb:51:in `send_activation_email'
now.271438+00:00 app[web.1]: [52c2ba12-f1fb-43ff-b988-79e7e3acb43b] app/controllers/users_controller.rb:21:in `create'
now.272883+00:00 heroku[router]: at=info method=POST path="/users" host=stark-beyond-04633.herokuapp.com request_id=52c2ba12-f1fb-43ff-b988-79e7e3acb43b fwd="58.188.21.207" dyno=web.1 connect=5ms service=1518ms status=500 bytes=1891 protocol=https