I have here three PCs connected to a LAN between them and to Internet through one of them (Internet Conncetion Sharing). The question is, how can I make them send e-mails locally and not via Internet. Do I need some special software (the main comp is running under Windows XP Prof and the other two has Win2000 and WinXP Pro) ?

Thank's in advance.

Does it have to be emails? Is this for sending messages out to the other two computers? If so, I recommend using the Messenger Service to do this. Take a look at this Microsoft Article for more information. By using that function you will be able to send messages that will popup on the screen instantly.

When I install a package with appache+mysql+php, I found a subdirectior with the program "sendmail.exe". My OS is windows 2000. The readme said that the program is support for mail() function in php code. If you can configured it properly, I think you could use php to support you need.

P.S. I failed to configure it. After I tried, no mail sent actually.

There is a program called exchange that i use at work and allows you to send internal emails on a network. It runs through Microsoft outlook. I dont know what the sort of prices you are looking at as the company have paid for it.

Try mercury mail and also the Pegasus mail client, it is free (both of them) and just do a search for Mercury mail and it will work on a LAN I used it on my own little LAN for testing purposes.