If it's a web page, it's a
web server, not a "LAN" server, which is a meaningless term. Servers come in all sorts of varieties, but it's the protocol that defines what kind of server it is, not what the server is attached to or what type of physical machine the server software is housed in. Whether a web server is for LAN use only, open Internet use, or both, it's still a web server, not a "LAN Server", file server, print server,
Exchange Server, Active Directory Server,
etc.,
etc.,
etc. Those items are simply the software server programs that may or may not be installed and running on a given server machine.
I'm afraid I cannot
assume that the same user ID applies everywhere. It's usually easier when it does, but some shops are more consistent than others. It's purely what local practices and standards dictate, not a fundamental architectural law that I can take for granted.
If you're running an all-Microsoft shop, you can
probably work out an Exchange plugin that will customize each user's copy of their email with their respective LAN login ID in the URL. Whether this is a good idea or not can be debated, but once again, that's up to local usage. What you can also do, however, is visit each LAN user's machine and switch on a special IE setting that appends a non-standard HTTP header containing the user's current LAN security credentials so that a "one-size-fits-all" URL can be used instead. If you do this, you also need a Windows-friendly SSO security Realm installed in the web server and in control of the webapp containing the JSP in question. That particular protocol is not a universal standard and applies only to Windows machines running IE on a LAN (unless someone has recently added it to the Apple web browsers). And even then the requisite IE function is switched off by default for security reasons.