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:




which was changed by company policy to:




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.