Support <surgemailHIDDEN@t@netwinsite.com> wrote:
>So, the answer is you can 'mostly' do it, but I'm certain you will wish you didn't try. :-)

Thank Chris!

For my case, the inside servers are Exchange, so it is IMO not an issue because I can configure the gateway also as smart-host. It is the default behaviour of Exchange that it delivers the internal Exchange-Exchange directly over local storage. Only when the recipients are not local (to Exchange), it will route the message to the smart-host, where the whole delivery cycle should start again. And because the gateway can verify the recipient per LDAP, loop is not likely to happen.

But I totally agree with you that such configuration is not optimal. Nevertheless, it is indeed required for a transition, partial upgrade scenarios, where the client do not want to give up its Exchange environment right now, at the same time do not expand its license neither and seeking for a long term replacement.