While i am trying this tool to find possible emails on my own domain its coming up with no results

Code:
root@bt:/usr/local/bin# dmitry -e security-need.com
Deepmagic Information Gathering Tool
"There be some deep magic going on"

HostIP:66.98.145.18
HostName:security-need.com

Gathered E-Mail information for security-need.com
---------------------------------
Searching Google.com:80...
Searching Altavista.com:80...
Found 0 E-Mail(s) for host security-need.com, Searched 0 pages containing 0 results

All scans completed, exiting

& when i am trying this tool on gmail.com its coming up with only 28 results

Code:
root@bt:/usr/local/bin# dmitry -e gmail.com
Deepmagic Information Gathering Tool
"There be some deep magic going on"

HostIP:72.14.254.83
HostName:gmail.com

Gathered E-Mail information for gmail.com
---------------------------------
Searching Google.com:80...
catalin.hritcu@gmail.com
offroad.commission@gmail.com
chris.samuel@gmail.com
adikurve@gmail.com
madhav.gadgil@gmail.com
umi.tanuki@gmail.com
hockeymineur@gmail.com
emialaddress@gmail.com
isabelle.barriere@gmail.com
tony.adamss20100@gmail.com
mhowell@gmail.com
andrewbadr@gmail.com
mikelotfi@gmail.com
keith.ansell@gmail.com
commahpune@gmail.com
PaulGTully@gmail.com
philip.hrvatin@gmail.com
rbtmgreen@gmail.com
kvkirankumar319@gmail.com
jeantoe@gmail.com
dtsimon@gmail.com
giraffeorders@gmail.com
qualitydag@gmail.com
BurkHufnagel@gmail.com
nrginmotion@gmail.com
12dsanders@gmail.com
nuttaphol.ma@gmail.com
gvanberg@gmail.com
Searching Altavista.com:80...
Found 28 E-Mail(s) for host gmail.com, Searched 0 pages containing 0 results

All scans completed, exiting

Now, my question is ::: why its not showing any single result for my domain & the second question is ::: why its only showing 28 results when searching gmail.com [we all know it should be much more]

Regards