For Office365, you may have firmware too old to do SHA-2 Encryption, so before proceeding, bring the firmware up to the latest and try again.
Then, for the email setup assuming it still messes up.
smtp.office365.com port 587, using STARTTLS (Do not choose "STARTTLS if available"). Make sure the login name and from address are identical.Also make sure both logins are set to System before you type them in.
Then go to CWIS > Properties > Services > Email > Setup and edit the From Field entry
And verify it is exactly the same as the other locations above. This field gets populated when you first setup SMTP, but does not get changed when you change the SMTP section later.
There are probably a hundred forum posts about scanning to various OS's from various MFP's, this particular printer running the latest firmware will scan to every single OS that supports SMB or FTP. So the settings are the problem if you cannot.
So to strip it down to the basics as we have literally nothing provided for troubleshooting, I will go in order of failures and cover them all.
Connections:
Check the gateway on the MFP, make sure it is identical to the one listed on the PC you are scanning to.
Verify the time/date on the MFP is within 3 minutes of the PC's current time (CWIS > Properties > General Setup > Date and time
In the scan setup, whether you are using a one-touch, a repository, a template or a scan to, all the basics stay the same
SMB to the IP of the computer (Don't bother with host names, it won't work), the port is going to be 445 unless you live in the stone age and are on Windows XP SP1 or earlier.
The Share name has no forwarding or trailing slashes of any kind, literally identical to the shared folder. So if the shared folder on the PC is scAn then that is exactly what you put on the printer setup, not scan, not SCAN, you put scAn.
There is no Default repository document path, leave it empty.
Authentication:
The login name is probably not what you type to login to the PC, and it absolutely has a password, you can log into a PC without a password simply enough using a keyboard, but you can't from a remote OS across a network, the printer is based in Linux/Unix, it is not and cannot be in a Windows Homegroup. To verify the user account, go in to the folder permissions. And don't put it on the desktop or anywhere inside the users profile, stick to the root of the drive. (Tell the printer to login using whatever the users info is inside the brackets)
Once scan is successful, right click the shared folder and pick Send To > Desktop (Create shortcut) if needed.
Those steps will 100% get scan to work on Windows Vista through Windows 10 on every Connectkey MFP. Linux and OSX will also work, but since I was given nothing to troubleshoot, I'm assuming Windows.