dpkg -l postfix

[Kaushal Shriyan]

Hi ALL

 dpkg -l postfix
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Installed/Config-files/Unpacked/Failed-config/Half-installed
|/ Err?=(none)/Hold/Reinst-required/X=both-problems (Status,Err: uppercase=bad)
||/ Name           Version        Description
+++-==============-==============-============================================
ii  postfix        2.2.10-1ubuntu A high-performance mail transport agent

what does it signifies, I know that if a package is not installed
there will be no O/p

Please make me understand

Thanks

Kaushal