The default From: header in mails sent out by diskcheck
("Disk Usage Monitor - diskcheck") confuses the MDA (Postfix
in this case), so that the header arrives at its destination
like this:

From: Disk.com, Usage.com,
        Monitor.com, -@my.domain.com,
        diskcheck.com

(I have postfix forwarding root mail to a remote machine,
which also runs postfix.)

Version-Release number of selected component (if applicable):
diskcheck-1.4-2 and diskcheck-1.4-4.1

Suggested fix:

Change line in diskcheck to read:

    set_default(conf, 'mailFrom', '"Disk Usage Monitor" <root>')

and change lines in diskcheck.conf to read:

    # Who to identify the mail as coming from.
    #mailFrom = '"Disk Usage Monitor - diskcheck"'