T=remote_smtp defer (-53): retry time not reached for any host

This can be caused by multiple things, however if it happens for each email, it's likely your exim databases are corrupt; to resolve this you should:

/usr/sbin/exim_tidydb -t 1d /var/spool/exim retry > /dev/null
/usr/sbin/exim_tidydb -t 1d /var/spool/exim reject > /dev/null
/usr/sbin/exim_tidydb -t 1d /var/spool/exim wait-remote_smtp > /dev/null

/scripts/courierup -- force
/scripts/eximup --force

Hard disk monitoring using SMARTD

smartd is SMART Disk Monitoring Daemon for Linux. SMART is acronym for Self-Monitoring, Analysis and Reporting Technology (SMART) system built into many ATA-3 and later ATA, IDE and SCSI-3 hard drives. The purpose of SMART is to monitor the reliability of the hard drive and predict drive failures, and to carry out different types of drive self-tests.

smartd works with following operating systems:

1. Linux
2. *BSD
3. Windows
4. Solaris etc

How do I Install smartd?

However, smartd is not installed by default. Following are distribution specific steps to install smartd:

Debian Linux:

apt-get install smartmontools


Red hat/Fedora Linux:

rpm –ivh kernel-utils
OR
up2date kernel-utils
OR if you are using Fedora Linux
yum kernel-utils


FreeBSD:

pkg_add -r -v smartmontools

Before configuring hard disk for SMART monitoring make sure your hard disk is SMART capable:
smartctl -i /dev/hda

Output:

Code:
smartctl version 5.34 [i686-pc-linux-gnu] Copyright (C) 2002-5 Bruce Allen
Home page is http://smartmontools.sourceforge.net/

=== START OF INFORMATION SECTION ===
Device Model: SAMSUNG SV2002H
Serial Number: 0395J1FR904324
Firmware Version: RA100-04
User Capacity: 20,060,651,520 bytes
Device is: In smartctl database [for details use: -P show]
ATA Version is: 6
ATA Standard is: ATA/ATAPI-6 T13 1410D revision 1
Local Time is: Tue May 2 15:44:09 2006 IST

SMART support is: Available - device has SMART capability.
SMART support is: Enabled


You can configure the smartd daemon by editing the file /etc/smartd.conf.

In above output the lines:
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

Indicates that it is SMART capable and it is enabled.


Configure SMARTD

Debian Linux

* Enable smart by editing /etc/default/smartmontools file.
* Smart Configuration file: /etc/smartd.conf
* Start/Stop smart: /etc/init.d/smartmontools start | stop

Red Hat Linux

* Enable smart by editing /etc/smartd.conf file.
* Smart Configuration file: /etc/smartd.conf
* Start/Stop smart: /etc/init.d/smartd start | stop

FreeBSD

* Enable smart by editing /etc/rc.conf file (add line smartd_enable=”YES”).
* Smart Configuration file: /etc/smartd.conf
* Start/Stop smart: /usr/local/etc/rc.d/smartd.sh start | stop

Example

You can put following directives in Smart Configuration file:
(a) Send an email to alert@anishonweb.com for /dev/sdb:
/dev/sdb -m alert@anishonweb.com
(b) Read error log:
smartctl -l error /dev/hdb
(c) Testing hard disk (short or long test):
smartctl -t short /dev/hdb
smartctl -t long /dev/hdb

Caution smartd is a monitoring tool not a backup solution. Always perform data backup.