The mailx package is installed, but the message "Error running'/bin/mailx" continues to occur.

Issue

• The log below related to mailx occurs continuously.

Oct  XX 11:07:08 XXXX abrt-server: Sending an email...
Oct  XX 11:07:08 XXXX abrt-server: Sending a notification email to: root@localhost
Oct  XX 11:07:08 XXXX abrt-server: /usr/sbin/sendmail: No such file or directory
Oct  XX 11:07:08 XXXX abrt-server: . . . message not sent.
Oct  XX 11:07:08 XXXX abrt-server: Error running '/bin/mailx'
Oct  XX 11:07:09 XXXX abrt-server: Duplicate: core backtrace
...

• Look at this KCS, it is recommended to install the mailx package, but the mailx package has already been installed.

libreport-plugin-mailx-XXXX.el7.x86_64
mailx-XXXX.el7.x86_64