I’ve never paid much attention to the rules used in filtering phishing, scams and so forth.

 

However, recently, I realized that my colleague’s emails were all going to my Junk Folder in Outlook.

 

I warning I get with her emails is (after I anonymize her email details):

 

First.Last@domain.com    appears similar to someone who previously sent you email, but may not be that person. Learn why this could be a risk

 

I sent her this warning message to dig further, and found out that her domain (company) asked

her to change her login email address to conform with a company-wide policy. So, her email used

to be:

 

FirstMiddle.Last@domain.com

 

which was changed by company policy to:

 

First.Last@domain.com

 

This change has seemingly resulted in the junk mail filtering.

 

This is not ideal. I understand that there are ways to bypass this filtering through whitelisting.

But I am more curious about the method and the effects of this method on legitimate email addresses.