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Network blocks

Traffic from certain ports may be temporarily blocked to protect against malicious network activity. A block is applied if:

  • the IP address is sending a large volume of spam emails;
  • complaints are received regarding the IP address;
  • the IP address is found in DNSBL spam lists — public blacklists for IP addresses and domains;
  • the IP address is blocked at the request of the local regulator.

You can view these locks in the Control panel. If you have resolved the cause of the block, you can submit an unblocking request. Each request is reviewed individually, and we do not guarantee a positive outcome.

Also, some TCP/UDP ports and access to certain internet resources are blocked by default. For more information, see the Blocked ports and internet resources.

View network locks

  1. In the Control panel, on the top menu, click Products and select Network Incidents.

  2. Open the Network locks tab. Each block specifies the socket and protocol, the blocking period, and the action taken on traffic that meets the blocking conditions:

    • discard — traffic is blocked completely;
    • redirect — traffic is redirected to an additional scrubbing system;
    • rate limit — traffic bandwidth is limited to the specified value (bytes per second).

  3. If the IP address is not displayed in the locks, but traffic is limited:

    3.1. Ensure the port is not blocked by default. We block some ports to protect the Servercore infrastructure. For more information, see the Blocked ports and internet resources.

    3.2. Ensure that the IP address is not blocked due to a DDoS attack. For more details, see the Blocked attacks.

    3.3. Check if the IP address is in any spam lists on the mxtoolbox website. If the IP address is present in spam lists, submit a request for unblocking.

    3.4. If the IP address is not blocked and is not in any spam lists, but traffic is still limited, create a ticket.

    3.5. Wait for a Servercore engineer to respond with the reasons for the block.

Submit a request for unblocking

Each unblocking request is reviewed individually; we do not guarantee a positive outcome.

  1. Create a ticket. In the ticket, specify:

    • the port that needs to be unblocked;

    • the purpose of using the port. If you plan to use the port for bulk mailing, specify the type of mailing, the number of emails in a batch, provide an example of the email, and state whether the recipient can opt out of the mailing;

    • the IP address for which the port needs to be unblocked.

  2. Wait for a response in the ticket from a Servercore engineer regarding the steps to take for unblocking.

    If the port was blocked due to the IP address being included in a spam list, we will request its removal. We cannot guarantee the result — spam lists are managed by third-party services, and they decide on removal independently.

  3. Resolve the cause of the block and report it in the ticket.

  4. Wait for a response in the ticket from a Servercore engineer regarding the decision.