I am with problems with the sending of emails, I was to see in cpanel what it was happening, in the menu "Manage Mail Queue", this showing "There ploughs currently 428 messages in the mail queue", somebody knows what it can be happening?

Thanks.

Well.. someone sending a mailing list, or someone using your server to spam or you have a problem with exim and the email is not being deliver.

try reinstalling exim:
on shell do:
/scripts/eximup --force

del all those emails on queue and everything should work normaly

if you are using qmail you can find a script to fix mail queue on
http://www.techfiles.org

This is a cPanel forum. Now why would he use qmail on cPanel ?