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Proofpoint - Attachment gets rejected



A customer is trying to send us an attachment (.zip) and its size is ~6MB and its only 1 file.

Why it is not coming through?


Status: Rejected
Final Rule: maxsize


Firewall rule:
maxsize : size greater than 25MB or Attachment count greater than 256 or Total Umcompressed Attachment size greater than 100MB or File count in archive greater than 256 or file depth in archive greater than 20


The file sit 1 (.zip) file with 1 file (.xlsb) and its only 6Mb


What should I look next?

Best Answer

  • MJ-perCompMJ-perComp Posts: 1,098
    Accepted Answer

    an XLSB file is natively a ZIP file with a number of substrutures, that can easily sum up beyond 20. Try increasing the depth to 30 for a test.
    If that still fails you better send the file to the labs, it might contain a ZipBomb.


This discussion has been closed.