sendmail 无法发送邮件怎么解决? 提示 No address associated with hostname [Linux][PHP][elinkvps]

[iugo]

环境:
debian 6.0
Apache 2
PHP 5

情况描述:
本来相安无事, 但是发送的邮件总被当作垃圾邮件. 我想作个调整.
然后修改
/etc/mail/local-host-names
/etc/mail/sendmail.cf
/etc/hostname
/etc/resolv.conf
/etc/hosts

后来就出错了, 提示

service sendmail restart
Restarting Mail Transport Agent (MTA): sendmail
hostname: No address associated with hostname

然后我尽量修改回原来的配置, 但是无用了...