Dear 8Ucloud customers,

To protect our network, IP reputation, and service quality, using our cloud servers to send spam, unsolicited bulk marketing emails, or other abusive email traffic is strictly prohibited.

Outbound TCP port 25 restricted on new cloud servers

From October 13, 2026, newly provisioned elastic cloud servers and cloud server packages receive a platform-managed security rule blocking outbound connections to TCP destination port 25. Customers cannot delete this rule in the control panel or override it with custom security group rules.

This restriction applies to outbound TCP destination port 25, not all email functionality. TCP ports 465 and 587 are not restricted by this change. For legitimate verification codes, order notifications, and similar messages, use a reputable authenticated SMTP service or email API and follow the provider's rules and recipient consent requirements.

Abusive email sending is prohibited

An open port does not authorize spam. The same anti-abuse requirements apply when using email relays, APIs, proxies, or other delivery methods. Confirmed abuse may result in service restrictions or suspension of the affected cloud servers, depending on the circumstances.

The new security rule applies to newly provisioned cloud servers and has not been bulk-applied to existing servers. The prohibition on abusive email sending applies to all users.

Please contact online support if you have questions about legitimate business email delivery. Thank you for your understanding.

8Ucloud
October 13, 2026