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How to prevent internal users from autoforwaring mails to external recipients

How to prevent internal users from autoforwaring mails to external recipients

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For reasons of their own, some users create Inbox rules to auto-forward their work mails to their private mail or other external domains. As an administrator thats not necessarily at desired scenario.

To prevent internal users from auto-forwaring mails to external recipients you can create a Transport Rule.

Log into the Microsoft Online Portal, and navigate to the Exchange Online Control Panel (ECP)

  1. Change the view so you are managing the entire organization, and not just your individual mailbox (Mail>Options>"Manage My Organisation" -- see top of picture below)
  2. Select "Mail Control" and make sure you are viewing the "Rules" tab (see left of picture below)
  3. Click the "New" button to display the "New Rule" dialog and start building a new transport rule (see center of picture below)

In the dialog "New Rule", clicking ”More Options” …

...will enable adding more conditions

After clicking ”Add Condition” twice you have a triple AND-condition

For the first condition, in the "If..." section pick ”the sender….” and then ”is external/internal”

In the ”Select Scope” dialog pick ”Inside the organisation”

For the second condition repeat the above with ”the recipient…”  and then ”is external/internal” and then ”Outside the organisation”

For the third and final condition pick ”the message properties…”  and then ”include the message type”

In the ”Select Message Type” dialog pick ”Auto-forward”

Finally set the Action to be taken if the above condition is met. Under the ”Do the following….” click ”Add Action”

Pick ”Block the message…”  and then ”Reject the message and include an explanation”

If the conditions are met and the message is rejected, a non-delivery report (NDR) is returned to the sender. You can create customized text, which appears in the NDR, to explain why a message was rejected (e.g. Auto-forwarding from internal to external is blocked)

Optional – name the rule

Click Save to save the rule.

 

Comments
  • Tak!

    Very useful.

  • Hi Jesper,

    I followed exactly the above steps, but no success, my incoming emails are still being forwarded to my personal address.

    I tried sending from external to my company email and then from internal to my company emails, in both cases it failed!

    Any ideas?

    Thanks

    Sharad

  • This only works for Outlook clients.  Kiosk accounts can still forward to personal email accounts.

  • Hi Team, need help on how we can prevert users to set up email forwarding from OWA

  • Tim is right, "This only works for Outlook clients. Kiosk accounts can still forward to personal email accounts."

  • I think it is better to hide the option to forward or redirect through RBAC. After connecting to Exchange Online through PowerShell run the following:

    New-ManagementRole -Name "Disable-Auto-Forward" -Parent MyBaseOptions
    Set-ManagementRoleEntry "Disable-Auto-Forward\Set-Mailbox" -Parameters DeliverToMailboxAndForward,ForwardingAddress,ForwardingSmtpAddress –RemoveParameter
    Set-ManagementRoleEntry "Disable-Auto-Forward\New-Inboxrule" -Parameters ForwardAsAttachmentTo,ForwardTo,RedirectTo –RemoveParameter

    Sign into the EAC click on Permissions > User Roles > Click on the Plus sign to add an additional Role Assignment Policy naming it whatever you want and under MyBaseOptions you will see the Disable-Auto-Forward option that you will want to place a check mark in. Save the Role Assignment Policy.

    Assign the Role Assignment Policy to the user(s) desired.

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