Sharing data with external domains has become a new normal in today's digital era. However, misconfigured external email forwarding can lead users to accidentally expose the sensitive Microsoft 365 information to attackers. Thus, we are here to guide you in verifying and managing your external email forwarding rules in Exchange Online.
Windows PowerShell Connect-ExchangeOnline
Get-Mailbox -ResultSize Unlimited -RecipientTypeDetails UserMailbox | Where-Object { $_.ForwardingSmtpAddress -ne $null -and $_.ForwardingSmtpAddress -notlike ‘Your-domain' } | Select UserPrincipalName, ForwardingSmtpAddress, DeliverToMailboxAndForward 
An in-depth report on external email forwarding offers valuable insights, such as the mailboxes that are forwarding enabled, email forwarding SMTP addresses along with respective mailbox details.
No Report Spotlighting External Domains in Native Solutions!
Yes, despite native solutions offering details on allowed external forwarding addresses, they lack a dedicated report that consolidates all external domains into a single comprehensive list.
AdminDroid offers an exclusive report on External Domains Configured in Mailbox Forwarding, that lets you find included external domains for email forwarding along with the internal email addresses.
AdminDroid’s Microsoft 365 email monitoring tool is an ideal solution to track external email forwarding rules in your Exchange Online. It enables swift detection and helps to take action against any suspicious external email forwarding activities, ensuring your Microsoft 365 environment remains secure and efficient.
Review the 'Mailboxes with External Forwarding Inbox Rules' report to verify if any inbox rules have been set up, allowing external forwarding for specific mailboxes.
Manage Microsoft 365 external users with AdminDroid and review all the external user activities, memberships, etc., to prevent potential data breaches.
An overview of email activities in Exchange Online, displaying all top mail readers, senders & receivers for a clear understanding and efficient mailbox management.
With AdminDroid, find susceptible external forwarding inbox rule configurations and modify them if they seem suspicious in your organization.
AdminDroid helps you to instantly access mailbox usage statistics and find top mailboxes that consume a high amount of storage in Exchange Online.
Effortlessly monitor both incoming & outgoing spam emails to identify the primary sources and targets of spam that affect your Exchange Online security.
AdminDroid's Exchange Online management tool is an essential asset for monitoring both inbound and outbound email forwarding in your Microsoft 365 environment. By staying vigilant and informed, you can effectively sidestep security challenges and maintain a secure, attack-free Microsoft 365 environment.
This error occurs when your Microsoft 365 admin has blocked the external email forwarding in your organization.
Connect-ExchangeOnlineSet-HostedOutboundSpamFilterPolicy -Identity Default -AutoForwardingMode On
This error occurs in Outlook and delivers an NDR (Non-delivery report) as you do not have the necessary permission to forward the email to an external domain.
This error occurs when you enter the external domain email address in the parameter –ForwardingAddress.
Set-Mailbox –Identity -ForwardingSMTPAddress This error occurs when the recipient's admin has implemented a transport rule to block certain emails. If emails are sent to the recipient that matches the criteria set by the admin, they will be blocked, and the sender will receive the above error message.
If you have set the execution policy settings to ‘RemoteSigned’, the above error will occur while running the PowerShell script.
Set-ExecutionPolicy -Scope Process -ExecutionPolicy BypassYou can set up an anti-spam outbound policy to allow external email forwarding while managing your organization's email security. Follow the steps below to create an external forwarding policy in Microsoft 365.
Similarly, you can allow external email forwarding for all mailboxes in your Microsoft 365 environment by following the steps below.
With AdminDroid, monitoring external email forwarding is as easy as pie!
Though we have configured external email forwarding rules for a specific external domain, it is highly essential to track the forwarding configured users to identify risky forwarding rules that could lead to data leaks or breaches.
The Auto Forwarded Messages report in the Exchange Online admin center provides details on users who have automatically forwarded messages to external recipients. Also, this report provides insights into how messages are being automatically forwarded from your organization's mailboxes to external recipients.
Additionally, it contains the following details that will help you to detect potential unauthorized or non-compliant email forwarding practices.
However, the report might not provide the deep forensic details necessary for complex investigations.
To efficiently monitor external forwarding in Exchange Online, you can create an AdminDroid alert to notify you whenever the external forwarding rule has been created.
You can use the alert policy template ‘Creation of external forwarded rule’ to generate alerts when a new external forwarded email rule is created in Outlook by Microsoft 365 users.
To create an alert policy from templates,
Disabling mail forwarding rules to external domains is a critical security measure to prevent data breaches, such as hackers stealing sensitive information or departing employees forwarding company emails to external addresses. Admins have the following methods to block auto-forwarding to external domains, ensuring only secure and necessary communications are allowed.
Here's an overview of each method with a brief description:
By implementing these methods, admins effectively safeguard against unauthorized email forwarding, thus protecting sensitive data and maintaining the integrity of their organization's communication channels.
AdminDroid helps to monitor inbound & outbound spam emails in your Microsoft 365 environment. Immediately block those suspicious email addresses from email forwarding and improve Exchange mailbox security!
Get AdminDroid Office 365 Reporter Now!