We get a lot of spoofing emails from external accounts. I know how to limit them but today I was surprised by something new to me. Just few days ago I have created new user and email account. And today this user account get spoofing email from external domain. How it's possible so fast?
I am not master of Exchange but from my point of view one user account or computer has been compromised. Is there any other way that someone get access to such information like our email address?
We run Office 365 Business Premium, and we started implementation of EMS P1.
Unfortunately we don't have Windows 10 enterprise.
Can you suggest how to increase security of our Exchange and mailboxes?