Sending email from APEX is not working

Can someone help me ?

Have you configured the mail settings in Internal Workspace?

No, I don't know how to do that

What did you chose for Send Immediately in the send-email process?

yes , I have selected Send Immediately option

And finally try Apex_mail.push_queue to send the unsent emails

I dont know if there are mails in queue , how do I check it ?

I dont know about tApex_mail.push_queue

Thanks VC

I defined the setings . It shows "mail sent ",but it is pending in the mail queue , and is showing the following error message.
The error message is :
ORA-24247: network access denied by access control list (ACL)

I tried some methods from googling for solving this , but didnt work

Regards
Umer

Edited by: Nice1 on May 13, 2012 9:18 PM

Is it possible to create a background thread which will send mail from APEX at predetermined time & date ?