How to Create Outlook Rules to Filter External and Internal Emails in Your Organization

Hello Microsoft Community!!

In our company I had hard time to segregate external emails from internal ones that came to my organization inbox folder.

I have created two folders to as below to segregate Internal and External emails to better organization and easier filtering of my messages

I was planning to automate the process of email segregation by creating Outlook rule to move emails that being received from from external domains to specific folder, but it's somehow challenging. 

First solution I tried to create an Outlook rule that will make an Exception to the (Global Address List) of our organization, which means any emails received and are not belongs to the organization (Global Address List) it will be moved to the specified folder according to the rule.

Unfortunately, it didn't work all the time and my email got messed up.
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After further research I reached the best way to target external emails to filter the message header of the received email, to be specific the header attribute (X-MS-Exchange-Organization-AuthAs) I noticed this attribute can have one of two values according to Message Header Analyzer as below:

Now if you create Outlook Rule through Outlook for Desktop in this example you can choose the condition ( With Specified Words in message header) then enter either of the specified values below:

Targeting External Emails put the following value:

X-MS-Exchange-Organization-AuthAs: Anonymous

Targeting Internal Emails put the following value:

X-MS-Exchange-Organization-AuthAs: Internal

In my case I targeted the external emails to be moved to the folder I created (Inbox-External) 

It should look like below, you can also add more rule in my case below I flagged the message: 

This method is also applicable if you are dealing with Outlook OWA rules as below:

At the end am happy to share this experience with the community and happy to engage for discussion if there are better way to do it :)