How to Forward Domain Email to an External Address Without a Mailbox
Question details
The user needs to route domain emails to an external email address without assigning an Exchange Online license, update the routing address when it changes, and ensure Outlook clients do not use cached old addresses.
- Product
- Microsoft Exchange Online and Outlook
- Device & OS
- not provided
- Scenario
- Setting up or modifying an email forwarding rule for a domain email address using a Mail User instead of a licensed mailbox.
- Observed behavior
- Emails need to be forwarded to an external address. When the external address changes, Outlook continues to suggest the outdated email address from its AutoComplete cache.
Ensure you have Exchange Administrator permissions in your Microsoft 365 tenant to create or modify mail users. If you are updating an existing external address, you will need the Exchange Online PowerShell module installed or access to the Exchange Admin Center.
Use Exchange Admin Center to Create a Mail User
The easiest way to forward domain email without an Exchange license is to create a Mail User in the Microsoft 365 Exchange Admin Center.
A Mail User acts as a directory contact with a login identity but does not have an associated mailbox. It simply forwards all received messages to a designated external email address, saving on licensing costs.
Log in to the Microsoft 365 Exchange admin center using your administrator credentials.
In the left-hand navigation menu, expand the 'Recipients' section and click on 'Contacts'.
Click 'Add a mail user'. Fill in the required details, including the internal domain email address and the target external email address where messages should be forwarded.
Click Save. The mail user will now seamlessly forward messages to the associated external address without requiring a mailbox license.
Update Forwarding Address via Exchange Online PowerShell
If you need to update an existing mail user's external forwarding address, using PowerShell is fast and ensures the old address isn't kept as a proxy.
Clear Outdated AutoComplete Entries in Outlook
Even after updating the routing address in Exchange, Outlook may cache the old address. You must clear the AutoComplete cache so emails go to the correct new address.
Manage Your Documents and Emails with WPS Office
While Exchange admin settings require Microsoft 365, you can handle all your daily document, spreadsheet, and presentation tasks using WPS Office. It's a lightweight, free alternative that offers excellent compatibility with Microsoft formats, making it easy to transition and save on licensing costs.
Frequently Asked Questions
Does a mail user in Exchange require a license?
No, a mail user does not require an Exchange Online license. It simply acts as a routing contact that forwards emails sent to an internal domain address directly to an external email address.
Why does Outlook still show the old external address after I changed it in Exchange?
Outlook saves previously used email addresses in its local AutoComplete cache and offline address book. You need to manually delete the old entry by clicking the 'X' next to the suggestion when composing an email to force Outlook to retrieve the updated address.
Can I keep the old external address as a proxy address?
When you update the external email address using the Set-MailUser PowerShell command, the previous address is replaced entirely. It does not automatically remain as a proxy address.
What should I do if the old address is stuck in Outlook contact cards?
If clearing the AutoComplete list doesn't update the contact card information, the issue lies within your local Offline Address Book (OAB). Try creating a completely new Outlook profile or configuring Outlook to run in Online Mode instead of Cached Exchange Mode to fetch fresh data.
