If you use dyndns dns service and receive the mail like this

FAILED:   updating boredom.gotdns.com: badauth: Bad authorization (username or password)

And you check your config is right, no mater what os, like debian or windows.

Use the command to test ddclient config,

root@myla:~# ddclient -daemon=0 -debug -verbose -noquiet

At the last output you will see

Move Windows LAMP to Debian 8 (Jessie) and use Nginx to replace Apache, also setup rewriting http to https.

for apt installing latest packages

root@boredom:~# echo 'APT::Install-Recommends "0"; APT::Install-Suggests "0";' > 99recommended

backup source

root@boredom:~# cp /etc/apt/sources.list{,.orig} && vi /etc/apt/sources.list

add testing sources
for Debian Jessie

My mail system is postfix on centos 5.5, it's too old, and I can't update now.

Build new mail system on day of unemployment.

The new one is is Debian8.

When you have done by Debian installed.

root at debian:~# netstat -ntulp |grep :25
tcp        0      0 127.0.0.1:25            0.0.0.0:*               LISTEN      654/exim4  
tcp6       0      0 ::1:25                  :::*                    LISTEN      654/exim4

root at debian:~# lsof -Pni :25
COMMAND PID        USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
exim4   654 Debian-exim    4u  IPv4  11812      0t0  TCP localhost:smtp (LISTEN)
exim4   654 Debian-exim    5u  IPv6  11813      0t0  TCP localhost:smtp (LISTEN)

remove exim4*