If you mean, can internet access be limited to the server and not be available to the local PCs the answer is probably yes. I'll leave it to others who have more hands-on experience to confirm that and provide any pertinent details.
For the second question, I presume that you are referring to mail server software. Maybe someone will have a specific recommendation. Here is a comparison of mail server packages that are available. What you choose depends partly on what you are running under (Linux vs Windows) and what features are important to you.
chrishea
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You can run a mail server on a LAN, yes. Exchange is probably overkill, if its Linux, there are loads of options...
jbennet
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jbennet
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