Email problem

[xav2]

i have zen cart 1.51 installed on Godaddy Deluxe with cPanel Linux server, with free email plans,
then i get the email problems.

here's some tests that i did :
ps: for all tests below, i set
E-Mail Transport Method to "sendmail"
E-Mail Linefeeds to "LF"
Emails must send from known domain to "No"

test 1
set Email Address (sent FROM) to "[email protected]" (this is email of godaddy domain name)
go to contact_us page, use "ask@ gmail mail" to send message
FAILED: no errors on contact_us page, but no message received in [email protected]

test 2
set Email Address (sent FROM) to "test@ hotmail mail"
go to contact_us page, use "ask@ gmail mail" to send message
SUCCESSFUL: the message is received in test@ hotmail mail

test 3
set Email Address (sent FROM) to "test@ hotmail mail"
go to contact_us page, use "[email protected]" to send message (this is email of godaddy domain name)
FAILED: no errors on contact_us page, but no message received in test@ hotmail mail


is anyone could tell what is the exact problem?
Godaddy server problem? Godaddy email plan problem? my Zen cart setting problem? other php problem?