Can't receive mails.

[baicunko]

Hi, I'm running Centos 5.6 and I did the perfect server tutorial with ISPConfig 2 but I didn't install ISPConfig 2 as I'm planning on hosting only one website. I installed webmin to control my server. My server is ganganadores.com
I can send mail and receive mails but see them on the webmin administration page.
My problem comes when i try to connect to the server by IMAP or POP3, when I add the mail to my blackberry it setups correctly, I can send mails but I can't receive.
I also tried on my iPhone but I don't know my mail configuration as I'm used to always having this cause another one gave me this data.
What can I do about this? I can't install SquirrelMail as it gives me error for not having installed php-common which is for 5.1.6 and I'm running 5.3.6
Any ideas?
Thanks

[baicunko]

Now i added mail.ganganadores.com as my server for receiving and sending mails on my iPhone and I can receive mails but I can't send
So summary
Blackberry can send but can't receive
iPhone the other way around.
Suggestions?

[baicunko]

iPhone working whenever it wants! Now it sends and receive. Blackberry doesn't wanna receive at all.
When testing mail I sometimes get this error when sending.
Delivery to the following recipient failed permanently:

test@gananadores.com

Technical details of permanent failure:
DNS Error: Domain name not found
named is up and running perfectly.
Suggestions?

[falko]

Are there any errors in your mail log (in the /var/log/ directory)? What's the output of

netstat -tap

? What's in /etc/postfix/main.cf?