Send & Receive Issues

How to Troubleshoot Client Emails Blocked by SpamCop in Outlook

WPS Content Manager Oct 1, 2026 868 views

Question details

The user needs to resolve an issue where incoming emails from clients are being blocked and rejected due to SpamCop blacklisting.

How to Troubleshoot Client Emails Blocked by SpamCop

Product: Outlook / Mail Server
Device & OS: not provided
Scenario: A user is attempting to receive emails from business clients, but the messages are being blocked by the recipient's mail host because of SpamCop.
Observed behavior: Incoming emails fail to arrive, and senders receive a bounce-back or error message indicating their message was rejected by a SpamCop block.

Before you start

Before proceeding, ensure you have an alternative method to contact the affected sender, as you will need them to provide the specific bounce-back error codes they received.

Solution 1Recommended

Obtain the Non-Delivery Report (NDR) and Error Code

Collecting the full NDR from the sender is the most crucial step in identifying whether the SpamCop block is due to sender reputation or a configuration issue on your host.

SpamCop blocks usually stem from the sender's IP address being flagged for spam or having a poor sending reputation. The exact reason is always detailed in the rejection email.

Contact the sender

Reach out to the client via phone or an alternative email address to inform them their message was blocked.

Request the bounce-back message

Ask the sender to forward or provide a full screenshot of the Non-Delivery Report (NDR) they received when the email failed.

Identify the error code

Locate the specific error code and server rejection reason within the NDR to determine the exact SpamCop listing responsible for the block.

Verify mail server details

Check with your email hosting provider (e.g., cPanel, Exchange) using the error code to confirm if the block is enforced by your incoming mail server settings.

Obtain the Non-Delivery Report (NDR) and Error Code

SpamCop Delisting: SpamCop is an automated system. If a sender's IP is blocked, they usually need to resolve their server's spam issues, after which SpamCop automatically delists the IP (often within 24 hours of no spam activity).

Solution 2

Whitelist the Sender and Test via Webmail

If you are using Outlook desktop, adding the sender to your Safe Senders list and testing on the web version can help bypass aggressive local filtering.

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Frequently Asked Questions

What is a SpamCop block?

SpamCop is a third-party blocklist service that identifies IP addresses sending spam or abusive emails. If a mail server's IP is listed on SpamCop, receiving mail hosts that use the SpamCop database will automatically block or reject emails originating from that IP.

How do I fix a SpamCop block if my IP is listed?

If your outgoing emails are blocked by SpamCop, you must identify and stop the source of the spam on your network (such as compromised accounts or malware). SpamCop usually delists IPs automatically after 24 to 48 hours of clean email traffic.

Why can I receive other emails but not from one specific sender?

If only one client's emails are blocked, it means that specific sender's email server or IP address has been flagged for poor reputation by SpamCop. Your mail provider is successfully receiving mail from reputable sources but rejecting the flagged sender.

Outlook & Email Problems