A user can set up forwarding in a few different ways: 1. The types of forwarding via this method are: forward, forward as an attachment and redirect. Set forwarding on their mailbox using OWA options.
Users can select to Stop or Start forwarding and enter the address to forward to. This one specifically is important as transport rules and remote domains can't block, it appears.
I implemented the Remote Domain method, but it only blocked emails forwarded by inbox rules. It did not block emails if the user set up forwarding in OWA.
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Block autoforwarding to external mail addresses.
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Did you mean:. The many ways to block automatic email forwarding in Exchange Online. Methods to stop auto forwarding As an admin, you have a few different ways to prevent forwarding of emails outside of your environment.
The main ways I have identified are listed below, along with a brief description of their pros and cons. Select the link to learn more: Remote Domain Pros: Applies to all the above-mentioned types of forwarding a user can set up. Quick and easy to configure. It only removes the option to set it up from view; it does not remove any rules already in place and for that matter, it continues to allow those rules to function though admittedly you could always run a script to null out the parameter.
Use If: You are a company that primarily uses OWA and have already ensured users do not have forwarding set to begin with. The downside to this method is that the user is not notified that their forwarded message is dropped. In addition, you can easily identify the users hitting this rule as well through PowerShell reporting or by the generating an incident report action. You may want to note that RBAC is cumulative, so if an administrator has an admin role that includes New-Inbox rule with the forwarding parameters, removing it with the steps above will not make it disappear.
This tips and tricks guide is also incredibly handy. Create a new policy and add all the management roles, including our new one.Auto-forwarding inbox rules can be used by hackers and rogue employees to exfiltrate data from your organisation.
Microsoft recommends that you disable this functionality by default using an Exchange transport rule. You can log into the Office Security and Compliance Center and click on your Office secure score recommendations. You can use our scripts here to detect Inbox Rules that forward externally.
Follow this guide to set up an Azure Function app via the Azure Portal, and secure the credentials of your Office delegated admin. Copy and paste the code below into your new Azure Function.
Prevent Users from Forwarding Mail to Internet Addresses
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Since these providers may collect personal data like your IP address we allow you to block them here. Please be aware that this might heavily reduce the functionality and appearance of our site. Changes will take effect once you reload the page. Search For Search Block Inbox Rules from forwarding mail externally in Office using PowerShell Auto-forwarding inbox rules can be used by hackers and rogue employees to exfiltrate data from your organisation. What if I need to add exceptions?User: person1 mydomain.
Scenario 1 from inside organisation Sender: person2 mydomain Recipient: person1 mydomain. Scenario 2: from outside organisation Sender: person2 hotmail. You can see from the above, the auto-forward will work if the email is sent from external domain. I can find Powershell commands to disable Auto-forwarding, but I only want to block auto-fowarding to external domains. When I created the Transport rule, I was testing it against a user which already had the forwarder configured.
It has become apparent the rule only works on forwarders enabled after the rule had been created. For scenario 2 to work sending from external I had to remove the "apply this rule if sender is inside organisation' condition from my transport rule. Self explanatory why. Adam CodeTwo. Get answers from your peers along with millions of IT pros who visit Spiceworks.
Hi team, I'm trying to prevent Auto-foward emails to external addresses. Any ideas? Many thanks for your time. Best Answer. I've sorted it now. Two things: When I created the Transport rule, I was testing it against a user which already had the forwarder configured.
Edited Jun 11, at UTC.
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RobClarke This person is a verified professional. Verify your account to enable IT peers to see that you are a professional. Check out this post to see if this helps. Replace Attachment. Add link Text to display: Where should this link go? Add Cancel. Insert code. Join me to this group. Read these nextKeep in touch and stay productive with Teams and Officeeven when you're working remotely.
Try it! You can stop this by creating a mail flow rule. From the Microsoft admin center, select Exchangemail flowand on the rules tab, select the plus sign and choose create a new rule. Then open the drop-down for apply this rule ifselect the senderand then is external internal. Select Inside the organizationand then OK. Choose add conditionopen the drop-down, select The message propertiesthen include the message type. Open the select message type drop-down, choose Auto-forwardthen OK.
Open the Do the following drop-down, select Block the messagethen reject the message and include an explanation. Enter the message text for your explanation, then select OK.
If a hacker gains access to a user's mailbox, they can auto-forward the user's email to an outside address and steal proprietary information. Stop auto-fowarding for email. Top 10 ways to secure Office and Microsoft Business plans.
Stop auto-forwarding emails
Learn more. Next: Support. Select More options. Name your new rule. Scroll to the bottom and select Save. Your rule has been created, and hackers will no longer be able to auto-forward messages. Stop auto-fowarding for email Top 10 ways to secure Office and Microsoft Business plans.
Expand your Office skills. Get new features first.While there are some legitimate reasons where a company may wish to allow auto-forwarding of business email, the vast majority of the time the best course of action is to simply disable email auto-forwarding functionality. My position on the value of user passwords alone is fairly well known: passwords alone are not good enough, you should consider properly implemented multi-factor authentication and other mitigating controls.
The following are step-by-step procedures for two methods of disabling email auto-forwarding in Office This method applies to all methods a user may leverage to attempt mail forwarding. A potential downside is that no notification is provided to the user when their attempt at auto-forwarding email is blocked.
This approach allows for more granular control over how rules around auto-forwarding are applied. If you found this article useful or would like assistance from our team of security experts, reach out to our team.
An administrator wanted to know if there was a way to clear rules in Outlook or with a PowerShell command. Yes, you can use PowerShell to check for and remove forwarding rules. Use the first cmdlet to check for forwarding rules. This cmdlet will list all rules in the mailbox and if they are forwarding rules, include the address the message is being forwarded to Get-InboxRule -Mailbox user-alias fl Name,Identity,ForwardTo,ForwardAsAttachmentTo.
Then use this cmdlet to delete the rule: Remove-InboxRule -Mailbox user domain. My own preference is to configure Exchange server to not allow automatic forwarding to the Internet, problem solved.Create an Office 365 Shared Mailbox and Add to Outlook
In Office and Exchange and newer, disable forwarding to remote domains in the Exchange Admin center under Mail flowRemote Domains. If This will allow you to block forwarding to all domains then create remote domains for the domains you need to forward mail to. In older Exchange servers, block forwarding in the Exchange admin center.
Users can set up rules to forward mail, administrators can configure Exchange to prevent users from enabling forwarding rules. See Disable automatic forwarding in Office and Exchange Server to prevent information leakage TechNet for the instructions. If you can't disable automatic forwarding to the Internet, create a transport rule that drops messages sent from the terminated addresses.
Add the addresses to a distribution group and create a transport rule that looks for mail sent from members of the distribution group. You can drop the messages or redirect them to another address this will alert you to the presence of a forwarding rule on the mailbox. This requires you to open the user's profile in Outlook, which can be time consuming if you need to check a lot of mailboxes.
It's not possible to do it using powershell. The final option is to either disable or delete the mailbox. If you need to continue monitoring the address, add the user's email address to another mailbox or public folder. Otherwise, allow the mail to bounce with an NDR or deliver it to a dropbox.
If you want to keep the mailbox around for a bit, you can configure it so it can't send email by setting the maximum message size allowed to 0. You can do this using a cmdlet:. Get-InboxRule Set-Mailbox. She also created video training CDs and online training classes for Microsoft Outlook.However they also represent a risk that needs careful and vigilant management by the admins of your tenant to ensure they are not being misused.
Mitigating Client External Forwarding Rules with Secure Score
These rules can be created through several interfaces, a desktop client, Outlook Web Access even an admin can use PowerShell to implement via the 'New-InboxRule' cmdlet. Users themselves are often unaware of the rules they have in place lets face it, who in their desktop client regularly reviews their own rules? It basically takes mitigation 4 from above and turns that into a one click experience, allowing you to quickly implement a Transport Rule to help mitigate client created rules that Auto-Forward to external addresses.
By using this control it will allow you create the Transport Rule above, you can then subsequently tweak the rule directly, for example if you wished to change the NDR text. This feature is now live within Secure Score. Remember, a layered approach is key to helping adopt your Organizations security posture. Also ensure you are reviewing this as part of your scheduled security reviews, you should be checking the Default Remote Domain and other Remote Domains you may have active have your desired settings in place.
A compromised tenant admin account, could see these settings altered. Review Client Auto Forwarding Rules - Half the challenge in developing any security posture is understanding your Organizations risk and exposure.
Using a script called 'DumpDelegatesandForwardingRules. This script can take a while to complete, as it iterates through each mailbox to check the rules rules are stored in a users mailbox as a hidden item.
Implementing a Transport Rule based around the following can stop emails that are set to be Auto-Forwarded to an external address. In summary you create a rule based on the following logic. There are numerous great blog articles out there on how to achieve this. How Can Secure Score Help? You can find this Security Control in the Advanced Action section of your queue. Vinny says:. July 25, at pm. Cian Allner says:.