SMTP server connections

I have a doubt about SMTP server connections. I use a SMTP server to send out emails from our office here. Theres a java program to do this. If I send out this programs class file to other people, will they be able to use the same smtp server connection? do they need to authenticate to the server? or do i have to use their smtp servers in the program instead of ours so that the email is sent out? If I have to do that what is the way to find out from windows what SMTP server a user is using?

thanks

Harmeet

[529 byte] By [harmeetsinghbawaa] at [2007-10-2 6:16:48]