I get slews of emails from /usr/share/sendmail/sendmail reporting that:

Subject: Cron <smmsp@alpha> test -x /usr/share/sendmail/sendmail && /usr/share/sendmail/sendmail cron-msp
/usr/share/sendmail/sendmail: line 820: /usr/sbin/sendmail-msp: No such file or directory

And indeed, it is right, there is no such program/link.

Because this is a remote node machine, and routs all email to a smarthost, trying to send email to itself always fails, and creates a pile of junk on the remote mailhost server.

I tried to stop it by aliasing root (on the remote) to a real user name, but to no avail (of course), since these are aliases for incoming, not outgoing.

So, two problems;
1) stop the repeating error,
2) redefine where root mail should go.

??

I'm getting the same thing using Postfix on Ubuntu.