email receiving problem postfix

[associates]

Hi,

I have postfix installed and it's up and running. I also run Dovecot as IMAP server and Squirrelmail as my webmail.

I am having a problem here. I can send emails out to external email addresses but unable to receive emails from external email addresses like yahoo.

My server runs on Ubuntu 10.04 (lucid) Server Edition.

I have attached the main.cf and the mail log to this post. The reason I can not put the details of main.cf is because it's got some urls in it and I am not allowed to post urls.

I am not sure if I have configured it wrongly in main.cf

I have checked to ensure that my domain is not blacklisted and it is not blacklisted. So I do not know why the server from yahoo refuse to talk to me.

Any help would be greatly appreciated.

Thank you in advance