Troubleshoot blocked SMTP ports - Gcore Documentation

SMTP ports 25, 465, and 587 are blocked when the system detects unusual outbound email traffic from a virtual server. This is a spam prevention measure.

Verify the block

To verify whether the ports were blocked, navigate to Support > Support tickets in the Hosting portal. A blocking notification appears as a ticket with the subject “SMTP ports have been blocked” in the list.

Support tickets section in the Hosting portal sidebar, showing the empty ticket list

Blocking policy

Per paragraph two (d) of the usage policy, servers cannot be used to send unsolicited emails, chain letters, or spam. Outbound email is restricted to users of services hosted on Gcore servers.

Request unblocking

Contact support and include the details that match the situation:

Scenario	Provide
Legitimate email was sent	The domain name of the service whose users received the mailing
No mailing was sent, but blocking notifications appeared	The server setting that caused excessive SMTP traffic and how it was fixed
No mailing was sent, no notifications appeared, but ports do not work	Confirm that no blocking notification was received and describe any recent network configuration changes