onmicrosoft.com accounts

Hi, looking to understand more about the onmicrosoft.com domain in O365 tenants, which I've seen some info https://support.office.com/en-us/article/About-your-initial-onmicrosoft-com-domain-in-Office...

Paul Stork
Aug 31, 2016
The .onmicrosoft.com users were either created before you synced your domain or created manually in O365. You can switch their UPN to be your corporate domain instead of .onmicrosoft.com and users should then be able to login with their corporate credentials (assuming you are doing some form of AD Connect or Sync). The one limitation as far as I know is that after switching the UPN suffix their profile properties won't sync fully since the pre-existing properties will be preserved. At least that is what I've seen in practice.

kodikotus33

Copper Contributor

Dec 29, 2021

I'm also a victim of this, I'm inundated with thousands of these onmicrosoft accounts that appear to be phishing attacks. Filter rules don't work they are still getting through. It's so old.

kodikotus33

Copper Contributor

Dec 29, 2021

kodikotus33

Here's a sampling.... it's a constant barrage;

xyhhssibei.onmicrosoft.com

dxphqvmrmu.onmicrosoft.com

zfjdsgydmv.onmicrosoft.com

vcwkyadega.onmicrosoft.com

Email address removed

uxngoheepsonmicrosoft.com

hghzoznmys.onmicrosoft.com