Postfix inbound issue

[Simon Powell]

All,
Anyone know the directives I need to change in my postfix main.cf to  
stop this happening ? Means I can get no external mail- internal  
works fine......which would be great if myself and test weren't the  
only two users.....;-)


OK, connected to server.domain.com...
< 220 server.domain.com ESMTP Postfix
 > HELO edit.dnsvr.com
< 250 server.domain.com
 > MAIL FROM:<postmaster at zoneedit.com>
< 250 Ok
 > RCPT TO:<simon at domain.com>
< 554 <postmaster at zoneedit.com>: Sender address rejected: Access denied

I usually work with Postfix but within the kolab setup I am a little  
wary of fiddling lest it is different in some way!
Cheers
Si