HDD install, LAN access for one dialup email account?

I have two systems, both hard drive installed, one holds the printer, and serves as the print server for both systems ( so I've got network LAN printing setup ). I also have nfs LAN access between each system, so file and remote logins are setup on both systems.

What I am having a problem with is, we use a single dialup access to the world, System#1 has email through the one access account, and downloads, then removes from the ISP email account, all the recvd emails. System#2, just downloads the email, and leaves the email on the ISP's server, so that System#1 is, more or less, setup as the "server" for email, in essence.

What I would like to do, is, setup System#1 to get, and distribute, email to itself, and System#2, and still remove the email from the ISP server.

Mostly, the target solution here, is, to get System#1 to recv emails only, and PASS "Debian Security Announcements" through a forward ( LAN access ) email account, to System#2 ( as it stands now, I "Save" these files to local disk, then nfs the saved email file over to System#2, in a setup folder. But System#2 has to open the files as files, and doesnt have KMail set to look in this folder for its emails, it downloads them from the ISP still )

Can KMail be set on System#2 to look in this folder for its emails, ONLY? Or do I need to go with the forwarding emails, setup a LAN email account for System#2, and set System#2 to access its email from this instead?

Whatever solutions, can it be "noobie" explained, I have never taken on something of this, nor the seriousness of what this is all about ( I have the theory, but no practical doings of network email setups )

Thanks for any, and all, information, advice, and assistance,
Ms. Cuddles