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Best Practices

MX Logic Blocking My Mails With “554 Denied CS [*]”?

By Sridhar Kakkillaya | 2 minute read

Your mails are blocked with the error message: “554 Denied [CS]  [*] (Mode: normal)  (in reply to end of DATA command)”. 

What does “554 Denied CS [*]” mean?

The mail was rejected by Mxlogic / Mcafee because of the content of the message.

Steps for verification

To check the IP reputation of a sending server, please to go to and enter the IP address in the TrustedSource Query box.

Mcafee assigns one of the 4 levels to email reputation.

  • High Risk
  • Medium Risk
  • Unverified
  • Minimal Risk

If the IP address in question has a minimal or unverified risk level, you can rule out rejections because of the IP blacklisting.

The message has been blocked solely because of the content.

What Can I do?

For senders who are not McAfee SaaS Email Protection customers, please do one or more of the following:

1. Contact the intended recipient and ask them to add the sending address or domain to their allow list

2. Contact the intended recipient and ask them to open a service request with McAfee SaaS Technical Support so that the message can be reviewed as a false positive

3. Send a copy of the message with the original headers to

See also the related article titled Best Practices for Organizations Sending to McAfee SaaS Email Protection Customers for additional information.

To challenge the scoring of a message rejected as spam, send the the following information:

  • Email address of sender
  • Email address of intended recipient
  • Date of message (within past 7 days)
  • Exact bounce message received
  • Subject of message (If available)


If you have further questions, send us an email.

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