In a previous post I wrote about how to use Realmd and SSSD to join Ubuntu 16.04 to active directory. This has been working fine, but I noticed my root mailbox had a bunch of repeated entries with the following:

root : problem with defaults entries ; TTY=pts/2 ; PWD=/root ;

It turns out, every time a user would execute a sudo command, it would send an email to root with the above error. After doing a bit of searching I found the reason. Basically, it’s not really an error, just noise since sssd does not support sudo rules for local users.

It’s an easy fix to stop this. Just edit your /etc/nsswitch.conf file.  Find this line:

sudoers: files sss

and change it to:

sudoers: files