1. unable to qualify my own domain name (windriver-OptiPlex-755) -- using short name
修改 /etc/hosts, 主機名 windriver-OptiPlex-755 後添加 .localdomain.com
127.0.0.1 localhost
127.0.1.1 windriver-OptiPlex-755.localdomain.com windriver-OptiPlex-755
2. stat=User unknown
DSN: User unknown
修改 /etc/mail/sendmail.cf
# "Smart" relay host (may be null)
DS[smtp-na.wrs.com]
重啓 sendmail 服務：
sudo /etc/init.d/sendmail restart
3. stat=Deferred: Connection refused by [127.0.0.1]
/etc/mail/sendmail.mc
Port=smtp,
Addr=127.0.0.1')dnl
Addr 改爲 0.0.0.0
重啓 sendmail 服務：
sudo /etc/init.d/sendmail restart