IBM Support

QRadar Network Security (XGS) does not send SMTP 541 response for blocked email traffic

Troubleshooting


Problem

QRadar Network Security (XGS) does not send SMTP 541 response for blocked email traffic in some instances

Symptom

For some SMTP clients and larger email attachments, a block response from the XGS appliance on SMTP traffic will block the traffic but does not send the expected SMTP 541 response to end the email attempt.  The XGS resets the connection like a standard TCP connection.  The client may continue sending the email attempt, instead of considering the attempt as failed per server response.

Resolving The Problem

  1. Ensure you have XPU 3806.21192 or later installed
  2. Add the following tuning parameter to the XGS appliance, in the Tuning Parameters policy:
Name: pam.email.block_large
Value: on

Document Location

Worldwide

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Document Information

Modified date:
31 October 2019

UID

ibm11101561