foreign domains and internet addressing

Hi,

I'm having an issue with a foreign domain we have set up and Internet
addressing. We're running Groupwise 5.5

The foreign domain is called external there are around 130 external users
in there. If I check these address book there email address shows up as
userid.PostOffice.Domain. This is what I would expect and how I want it to
appear.

However, for new users I create in the foreign domain, when I check their
address in the address book their address appears as
userid@internetdomain.com. This the appends the internet domain set at the
Groupwise system level. Mails sent using this contact are not delivered
because that address doesn't exist.

We have changed nothing, I'm just wondering why this would start happening
for new users.

Any help would be much appreciated.