Forum Discussion

Copper Contributor

Mar 25, 2020

Office365 groups spam emails

Hi, My company recently experienced a spear phising attack. Luckily, we discovered it before anything happened. The email was sent to one of our Office365 groups and was freely distributed to al...

office 365

Spam filter

VasilMichev

MVP

Mar 25, 2020

They do, and they also have their own Junk E-mail folder where such messages should be placed. Since that didn't happen in your case, I'm guessing the message wasn't detected as spam at that point. There can be numerous reasons for that, but instead of guessing, go ahead and run a message trace - it will give you all the necessary details.

rav-i-den

Copper Contributor

Mar 25, 2020

VasilMichev

Hi Vasil,

Thank you for your answer. You are right the message did pass the group mail spam filter (the one saying delivered) but not for the users as you can see from the image. Do you know if there is anything to do, so this won't happen in the future?

Best regards,

Rasmus

VasilMichev
MVP
Mar 26, 2020
I can only guess - all the details you need are in the message trace/detailed message trace and the message headers. It might be that it failed the dkim check because of the "forward" to the individual users, or the few seconds it took to do that were sufficient for the EOP filters to start recognizing it as actual spam, etc.