Alias email address getting replaced by primary email address - invalidates routing rules

Question

Alias email address getting replaced by primary email address - invalidates routing rules

Kathy Blasco 101

We have rules setup to route messages based on the header email address which is an alias address.
We are finding that if the message is sent using Outlook on an android phone, iPhone, MAC, or outlook on the web the header email address changes to the primary email address. This behavior invalidates our routing rule based on the alias email address.
The only time we are seeing the alias address retained is if the email originates from Windows desktop outlook or an outside application such as gmail. Gmail worked from an android phone and in chrome.

When reviewing the message trace it appears the address is changed from the sender side not the recipient side. The messages that retained the alias shows they are 'resolved' to the primary address.

Is there an outlook setting that prevents the alias email address from being replaced with the primary email address?

My current outlook version is:

Windows Desktop: Version 2010 (Build 13328.20154 Click-to-Run)
Android: Version: 4.2039.2 (42039817)

@Becky Filo

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Answer 1

Andy David - MVP 157.4K MVP Volunteer Moderator

What you are seeing is by design when messages are sent from an authenticated user.
The only reason Outlook appears not to work this way is because you are using the Offline Address Book in cached mode.
If you were to set Outlook in online mode or set the following registry key:
https://support.microsoft.com/en-us/help/831124/how-to-force-outlook-2010-outlook-2007-or-outlook-2003-to-resolve-prox

it would work the same way as the other clients and resolve the proxy / alias to the primary SMTP address.

Anonymous messages sent from outside of Exchange do not resolve the sender address as you have seen as well.

Kathy Blasco 101 Reputation points

2020-10-21T18:05:12.76+00:00

Hi @Andy David - MVP
Thanks for the information. When I look in the registry I am not finding a Cached Mode entry. My Office version is 18.2008.12711.0. I am assuming the change needs to take place from the sender's device? My Windows Outlook Desktop app is working. How would I correct OWA, android, MAC, and iPhone?

.cc @Becky Filo
Andy David - MVP 157.4K Reputation points MVP Volunteer Moderator

2020-10-21T19:25:38.563+00:00

Hi anonymous user-4579
You would need to add that registry key manually as its not there or simply set Outlook to an online profile.
and yes,
The change would need to happen on the senders Outlook client

For the other clients, you can not change their behavior as they use the Online Address Book by default.
So just to be clear, if you make the changes I mentioned above to the Outlook for Windows clients, then messages sent from these clients will also fail your rules.
Right now, in the default setting, Outlook works the way you want it to, the other clients do not.
that is by design when messages are sent from authenticated senders so you will need to change your rules or processes.
JeffYang-MSFT 6,261 Reputation points Moderator

2020-10-25T10:43:14.09+00:00

Hi anonymous user-4579.
Just checking in to see if above information was helpful. If you have any further updates on this issue, please feel free to post back.
Kathy Blasco 101 Reputation points

2020-10-28T17:23:46.853+00:00

Hi @Andy David - MVP and @JeffYang-MSFT
I understand what you are saying. It kind of defeats the purpose of an Alias address.

We will note that using an alias address for message routing is not a viable solution.

Thanks!

.cc @Becky Filo
Niklas Lehtinen 1 Reputation point

2020-12-07T12:36:13.437+00:00

Question: If I remove user from the GAL, will it work then? Because then the address can't be found from GAL, there shouldn't be user where OWA could reference?

Answer 2

morbraden 41

Looks like a solution was found for this specific issue.

I also had a similar question of this nature and here was my solution:

Visit https://admin.exchange.microsoft.com/#/settings
Click on "Mail Flow"
Check the box "Turn on sending from aliases"

Wait a few minutes and you should then be able to send and receive from an alias address without Exchange resolving it to the primary alias (proxy address) before delivery.

morbraden 41 Reputation points

2023-03-15T15:42:34.65+00:00

Oddly enough, turning on sending from aliases fixed my issue with receiving to an alias. Microsoft magic I guess.
Victor Ivanidze 101 Reputation points

2023-03-28T18:35:11.7266667+00:00

Hi @latavalle, how does it help to see the alias address in Inbox view (Outlook for Windows)?
morbraden 41 Reputation points

2023-03-28T18:53:39.9466667+00:00

@victorivanidze-0112, it is usually less about seeing the proper alias (SMTP proxy address) in outlook and more about applying mailbox rules. In my instance, Exchange was resolving the domain to the primary tenant domain prior to delivery to the user's mailbox. So, if an email were sent to ******@domain2.com (alias) it would resolve to ******@domain1.com (primary domain) and show up that way in the user's inbox. This means most user level outlook inbox rules would not work if they are looking for emails sent to ******@domain2.com to apply a specific flag or move the message to a specific sub-folder. All of this of course is assuming a company relies on email alias in their workflows. Other solutions exist that may be better, but in this instance, having the proper email alias appear in the message "to" field was important.
Kathy Blasco 41 Reputation points

2023-03-28T19:15:50.8633333+00:00

Hi @Victor Ivanidze

My original need was to route messages to mailbox folders. Power Automate would then lick up the email and complete processing on it. If the alias resolved to the primary address the routing would not work. Somewhere along the line that setting was checked that @morbraden mentions and now the routing works. We don't use these solutions anymore as we came up with workarounds at the time. It's good to know that we can use an alias for future developments if need be.
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Answer 3

Bartosz Jabłoński 1

Hi,

@Kathy Blasco
I found a solution to the problem, at least for the OWA - yes, it gets already email to the re-written primary address and this is how it looks to recipient and to the OWA client, but when you check the msg details in MHA (http://mha.azurewebsites.net/) you will see the original header has the alias in there.

OWA gives you possibility to act upon them "if the message header contains". I created such rule and it moved the message to the right folder.

I know you probably used the Transport Rules in Exchange Admin Center and I didn't test it there (time constraints), but I believe the idea will be the same behind it, so give it a try.

For OWA at least, even with visible re-writing, it works :)

Regards,
Bart

Kathy Blasco 41 Reputation points

2021-08-11T13:39:52.75+00:00

Hi @Bartosz Jabłoński and @Andy David - MVP ,
Since the changes need to occur on the sender side we opted to require they include a string in the subject to route emails to the proper folder. We can't guarantee where the user sends the message from or that any changes would be made on thier devices to properly retain the to address in thier emails.

Thanks for the info.

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Alias email address getting replaced by primary email address - invalidates routing rules

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