在目录\apps\redmine\htdocs\config下找到configuration.yml, 打开，修改配置，如下：

email_delivery:
delivery_method: :async_smtp
async_smtp_settings:
# delivery_method: :smtp
# smtp_settings:

address: smtp.163.com
port: 25
domain: "163.com"
authentication: :login
user_name: XXXX@163.com
password: ******
# enable_starttls_auto: true

Redmine邮件发送功能配置