Mailbox Email Forwarding
Mailbox Email Forwarding can be configured by any user for their mailbox,
allowing forwarding to external (ForwardingSmtpAddress) or internal
(ForwardingAddress) email addresses.
# Lists all mailboxes with a forwarding address configured from Mailbox Settings.
Get-Mailbox -ResultSize Unlimited | Where-Object { ($Null -ne $_.ForwardingSmtpAddress) } | Select Identity,Name,PrimarySmtpAddress,ForwardingSmtpAddress
The email forwarding configured on a given mailbox can also be visualized from the Microsoft 365 admin center (https://portal.office.com/Adminportal/Home/?#/users).
Mailbox Inbox rules
Mailbox Inbox rules can be configured by any user for their mailbox, allowing forwarding to external or internal email addresses as well as deletion of received emails.
# List all mailboxes's Inbox rules for the given mailbox.
Get-InboxRule -Mailbox <EMAIL> | Select-Object Identity,Name,Enabled,Description | Format-List
# List all mailboxes's Inbox rules with ForwardTo, RedirectTo, ForwardAsAttachmentTo, or DeleteMessage actions.
$Mailboxes = Get-Mailbox
Foreach ($Mailbox in $Mailboxes) {
Get-InboxRule -Mailbox $Mailbox.Name |
Where-Object {($Null -ne $_.ForwardTo) -or ($Null -ne $_.RedirectTo) -or ($Null -ne $_.ForwardAsAttachmentTo) -or ($True -eq $_.DeleteMessage) } |
Select-Object Identity,Name,PrimarySmtpAddress,Enabled,ForwardAsAttachmentTo,ForwardTo,RedirectTo
}
Mailbox Mail Flow / Transport rules
Mailbox Mail Flow / Transport rules can only be configured by
Exchange Admin users, and allow actions to be taken on in transit emails.
For instance, a blind copy (i.e with out disclosure to the sender or recipients) can be send to external or internal email addresses.
# List all Mail Flow / Transport rules.
Get-TransportRule | Select-Object *
# List all Mail Flow / Transport rules that send a copy of received emails.
Get-TransportRule | Where-Object { ($Null -ne $_.BlindCopyTo) } | Select-Object *
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