Can send email but not receive it.

Your postfix setup does not believe that it has to do local delivery for addresses in the limecat.org domain so it tries to relay the mail and finds that this is prohibited - hence the error message.

Local delivery is controlled by the value of mydomains in /etc/postfix/main.cf. The instructions you used do not appear to set a value for mydomains so it will default to '$myhostname localhost.$mydomain'.

The instructions you followed tell you to set the hostname to server1.example.com and does not set the domainname. Postfix will then take the value of hostname, minus the first component (server1 in the example) as the domainname for the mydomain variable.

postconf | grep ^my[dh]

will get you the current values of the important configuration variables.

Working example:

root@fremont root # postconf | grep ^my[dh]
mydestination = $myhostname, localhost.$mydomain, $mydomain
mydomain = clissold.nl
myhostname = fremont.clissold.nl
root@fremont root #

I'm guessing that your mydomain is something other than limecat.org.