​How to allow using a Microsoft Account (e.g. [email protected])  to access a share instead of using a Windows Local User?

Credit to DaKarli

From SSH of your UnRAID Server type the below commands

mkdir -p /boot/config/custom/etc/samba
nano /boot/config/custom/etc/samba/usermap.txt

Add the following, replacing user with your unraid username name and replacing [email protected] with your Microsoft account email address

user = [email protected]

Press CTRL + X and then Y to save and exit

Now stop your array and go to your SMB settings in the GUI and add the following line under the Samba extra configuration section

username map = /boot/config/custom/etc/samba/usermap.txt

Now simply start the array and everything should work as expected and you should no longer have a problem to use your [email protected] Microsoft user account to login into your Unraid Samba share.