Email doesn't work anymore - solved easy

I have some sites hosted on a centos server that are using either the php mail function or sendmail. I haven’t change anything in the server’s configuration except installing the virtualmin updates, when I was notified. I suspect one of these updates changes something to postfix, maybe, though I don’t have much knowledge of how this is working.
The problem is I don’t know where to start and what to change back/fix. If anyone has any ideas, please share them. Any advice is appreciated.
My php scripts are announcing me that the emails have been sent; but they aren’t.
For what it matters, I have virtualmin 3.83.gpl GPL, centos CentOS Linux 5.5 kernel, webmin 1.530, php 5.1.6-27.el5_5.3, apache 2.2.3.

If you have any idea about how to fix my issue, please remember that I’m not an expert and give all the details, a step-by-step for noobs :slight_smile:
Thank you!

Also, from within webmin the postfix page doesn’t load, looks like is loading forever and if I restart the postfix I got this “postfix/postfix-script: fatal: the Postfix mail system is already running”.
I’m thinking to reinstall it but I’m afraid I’ll make more damage.

After a little thinking I’ve uninstalled and reinstalled the postfix and now is working.