AlibabaCloud DirectMail is transactional email service from AlibabaCloud. It is like Amazon SES, MailGun, SendGrid etc…
They have 3 differnt mail server hostname depending on region. Unlike other SMTP providers, they allow email using port 80.
SMTP service address (China East 1): smtpdm.aliyun.com
SMTP service address (Singapore): smtpdm-ap-southeast-1.aliyun.com
SMTP service address (Sydney): smtpdm-ap-southeast-2.aliyun.com
SMTP port: 25, 80, 465 (SSL encrypted).
Note: Port 25 is currently disabled to maintain ECS security. If your sending application is deployed on Alibaba Cloud ECS, we recommend that you use port 80 when SSL is not checked, and use port 465 when SSL is checked. Besides, we support explict ssl/tls functionality on port 25 or 80 with “STARTTLS” smtp cmd.