Redmine

I am using Redmine 2.5.2 now and when I tried to send test mail,an error occurred.

Here is the system infomation:

And here is the mail configuration:

===========================================
production:
email_delivery:
delivery_method: :smtp
smtp_settings:
address: smtp.auto-linked.cn
port: 25
authentication: :login
domain: 'auto-linked.cn'
user_name: MYACCOUNT@auto-linked.cn
password: MYPASSWORD

===========================================

Any suggestion would be helpful.
Thanks a lot.