In Office365, Exchange Online Protection is an Anti-Spam & Anti-Malware agent which filters spam & virus automatically, However there are chances still Spam mails would be delivered to Office365 Users as there are no perfect systems to catch 100 % spam mails, We have lot of options to control as an Admin/user:
Let us discuss few here:
Spam mails are decided based on the SCL(Spam Confidence Level) rating: Refer to Spam confidence levels these SCL's are being rated based on Connection & Content Filtering.
Connection Filtering is based on IP Reputation of the sender, If the sender IP is on reputed blacklist then Office365 Servers rejects the messages at connection level, this cannot be recovered and non-traceable.
Content Filter : Is where you can manage/control spams:
Below example Transport Rule can be created to Increase SCL
Below is where you can set the Spam Actions : Most used : Quarantine or Junk
Below are the additional Spam actions, Ensure you Turn on relevant one to avoid False Positives.
In next Part I would be covering more in-detail.......