用using at 對嗎？

suggest to write as "using in office"

the whole sentence would be:

In order to know the email forwarding setting, please inform us what kind of server is using in office.

In order to know the email forwarding setting, please inform us what kind of server being used in the office.

I think that will be........
please inform what kind of server is used in your office.

or

what kind of server in your office..........