I am a Linux newbie. We have a mail server bringing in mail from a cable ISO and distributing the mail over ethernet network. The Red Hat 6.2 server is named mail on domain tri-superior.com. Right now we have no email because some file on the server is full. The gentleman we hired to set this up is no longer in the area and I do not know who to ask for help. I am trying to learn Linux but this is beyond my current abilities and we need the mail.
Can anybody point me in the right direction to locate this or these full files so I can start doing proper maintenance and keeping them cleared out?
Thanks

What are the exact error messages?

Sorry this has me totally stressed out. This mail server has been running for over 2 years without a hiccup. Now it has just stopped forwarding the mail and the ISP cable company insists that everything is perfect on their end. We have had no interruption on our browsers. The ISP service says it has to be something in the mail server that now has a full file. I have no idea where to look. If I can find the full file I can start watching and emptying it.
As far as I can tell Linux is still operating without a hitch other than this 24/7 on an older i486. Very impressive.
I tried to send an email from the server "mail" and got the message "mail not sent" "sending error: 452".

Thanks for your patience I found the files I needed to clear in /var/spool/mail. Email started right up once I eliminated the hundreds of unanswered emails from the account that was not removed for a former employee.