lacal-host-names for external mailserver

[unsichtbare]

OK, I know this problem has been covered so many times, so please excuse if the answer is right under my nose (i did quite a bit of searching, though...)

I have a website, http://www.ritochpowell.com where mail is hosted in their office, on their exchange server (DNS is not managed by ISPConfig, rather at net-sol)

The website is set to External Mailserver
There are no MX records
www.ritochpowell.com IS in etc/postfix//local-host-names (if I delete this, I get about 1 email before it is added back to the file

I can not send mail to anyone@ritochpowell.com

Where am I going wrong?

[till]

As described in all the other posts, set the website AND the co-domain to external mailserver in ispconfig