Thanks for the replies!
On my original post I left out a BIG part of what I have done that could explain why I'm not getting any mail from the system.
I have actually switched MTA. I stopped using sendmail and now I have postfix up and running (this was done at the same time that I changed hostname).
I'm able to receive/send mail just fine. I use virtual mail boxes, and I actually use roundcube to send and check mail messages (which is working very good
). Yesterday I used the "mail" command to send an e-mail from the root user to my gmail account, and this also worked just fine. But whenever I try to send an e-mail to root@localhost I don't receive anything.
Here's one of the messages in maillog: to=<root@myhost.mydomain>, relay=none, delay=0.58, delays=0.01/0.04/0.53/0, dsn=5.4.6, status=bounced (mail for myhost.mydomain loops back to myself).
I also checked mail queue and its empty.
I'm almost sure that this problem happened when I switched MTA. Any new ideas on this problem?