Microsoft Exchange Control Panel couldn't proxy user '%1' from site '%2' to site '%3'. There are no Client Access servers ...

Microsoft Exchange Control Panel couldn't proxy user '%1' from site '%2' to site '%3'. There are no Client Access servers on the destination site that can be used as proxy targets.

The list of servers considered and the reason for not using them is:
-----
%4-----
An empty list indicates that there are no Client Access servers in the site configured with an internal URL.
English
English (United States)
Deutsch (Deutschland)
German (Germany)
Español (España)
Spanish (Spain)
Français (France)
French (France)
italiano
Italian
한국어
Korean
Русский
Russian