POAs in your GroupWise system should be located behind your firewall. If GroupWise client users want to access their GroupWise mailboxes from outside your firewall using the Windows client or the Linux/Mac client, you should set up a proxy server outside your firewall to provide access, as described in Section 36.3.1, Securing Client/Server Access through an External Proxy Server. WebAccess client users access their GroupWise mailboxes through their Web browsers, so your Web server handles the access issues for such users.