Sigma rule: Suspicious PowerShell Mailbox SMTP Forward Rule

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-14187ca615fe, updated 2026-03-01T00:00:00.000Z.

SigmaHQ marks this rule as deprecated.

Rule

Title
Suspicious PowerShell Mailbox SMTP Forward Rule
Status
deprecated
Level
medium
Author
Nasreddine Bencherchali (Nextron Systems)
Date
2022-10-26
Modified
2026-03-01
File
deprecated/windows/posh_ps_exchange_mailbox_smpt_forwarding_rule.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects usage of the powerShell Set-Mailbox Cmdlet to set-up an SMTP forwarding rule.

Log source

product
windows
category
ps_script
definition
Requirements: Script Block Logging must be enabled

Detection

selection:
    ScriptBlockText|contains|all:
        - 'Set-Mailbox '
        - ' -DeliverToMailboxAndForward '
        - ' -ForwardingSmtpAddress '
condition: selection

False positives (as the rule lists them)

  • Legitimate usage of the cmdlet to forward emails

Tags

  • attack.exfiltration

References

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/deprecated/windows/posh_ps_exchange_mailbox_smpt_forwarding_rule.yml

Sources and licences

  • SigmaHQ

    "Suspicious PowerShell Mailbox SMTP Forward Rule" by Nasreddine Bencherchali (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/deprecated/windows/posh_ps_exchange_mailbox_smpt_forwarding_rule.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: Suspicious PowerShell Mailbox SMTP Forward Rule",
entity page, dataset version ref-14187ca615fe, updated 2026-03-01T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/15b7abbb-8b40-4d01-9ee2-b51994b1d474 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 15b7abbb-8b40-4d01-9ee2-b51994b1d474, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.