CIPP Mailboxes

Exchange Online mailbox operations through CIPP. The four supported tools cover the highest-frequency MSP mailbox tasks: listing mailboxes for inventory, auditing permissions during BEC investigations, setting OOO for leave/offboarding, and configuring forwarding for transition periods.

Anti-triggers

• The BEC investigation report itself — cipp_bec_check is in cipp-users. This skill covers the mailbox layer of the remediation that follows it.
• A whole offboard — cipp_offboard_user in cipp-users sets OOO, forwarding, and shared-mailbox conversion in one call; reach for the individual tools here only when you need step-by-step control.
• Inbox rules, transport rules, mail flow, or quarantine — none are in CIPP's MCP surface. Use the m365 plugin (Microsoft 365 Mailboxes) or Exchange Online PowerShell.
• Who signed in to or accessed a mailbox — that is unified audit log territory; use cipp-alerts.

Tools

cipp_list_mailboxes

cipp_list_mailboxes(tenantFilter='contoso.onmicrosoft.com')

Returns all mailboxes (User, Shared, Resource, Equipment, Room) with userPrincipalName, recipientTypeDetails, archiveStatus, litigationHoldEnabled, and storage usage. Use as the entry point for any mailbox audit.

cipp_list_mailbox_permissions

cipp_list_mailbox_permissions(tenantFilter, userPrincipalName='user@contoso.com')

Lists all delegates and full-access trustees on a mailbox. Critical during BEC investigations — attackers commonly grant themselves Full Access or add a forwarding rule. Always run this on a compromised mailbox before remediation.

cipp_set_out_of_office

cipp_set_out_of_office(tenantFilter, userPrincipalName,
                       enabled=true|false,
                       internalMessage?, externalMessage?,
                       startTime?, endTime?)

Use during offboarding (permanent), planned leave (scheduled), or as a tactical control after disabling an account so external senders get a clear bounce-equivalent.

cipp_set_email_forwarding

cipp_set_email_forwarding(tenantFilter, userPrincipalName,
                          forwardingAddress?,
                          deliverToBoth=true|false,
                          disable=true|false)

Set disable=true to remove existing forwarding — this is the first action during BEC remediation. Set forwardingAddress to redirect a leaver's mail to their manager during transition.

Workflow patterns

BEC investigation — mailbox layer

1. cipp_list_mailbox_permissions — capture current delegates before changes
2. Check the BEC report from cipp_bec_check for forwarding rules and inbox rules
3. cipp_set_email_forwarding(disable=true) — remove any forwarding the attacker added
4. (Outside CIPP scope: review and remove malicious inbox rules via Graph or PowerShell)
5. Document the original delegate list — restore legitimate ones after cleanup

Offboarding — mailbox handling

If cipp_offboard_user is run with convertToShared=true, CIPP handles the mailbox conversion internally. For manual control:

1. cipp_set_out_of_office(enabled=true) with a clear "no longer with the company" message
2. cipp_set_email_forwarding(forwardingAddress=manager@contoso.com, deliverToBoth=true) to keep a paper trail while routing to the manager

Planned leave coverage

cipp_set_out_of_office(tenantFilter, userPrincipalName, enabled=true,
                       internalMessage='Out until 2026-05-15. Contact teamlead@.',
                       externalMessage='I am out of office. Please contact our team at...',
                       startTime='2026-05-01T00:00:00Z',
                       endTime='2026-05-15T00:00:00Z')

Scheduled OOO with start/end times is preferred over enabled=true without dates — it auto-disables on return.

Caveats

• These tools are scoped to the mailbox-level operations CIPP exposes. Transport rules, mail flow, quarantine, and per-tenant Exchange settings require either CIPP UI workflows or direct Exchange Online PowerShell.
• cipp_set_email_forwarding(disable=true) removes all forwarding — including legitimate ones. Capture state first.