NetBSD, as almost all Unixes, brings a mailserver (Postfix) along with its standard system.
This mailserver is enabled by default to let outgoing mails through, but most mailservers won't accept mails from dial-up networks. So the most common way is to use another mailserver with your common mail account to relay mails.

Your task is to write a small wrapper that does the authentication needed for most SMTP relays, such that a user only has to insert his account details for e.g. Gmail and then can relay the system mails there.

You should also take into account relaying the system user's mails to that account or document how you would do so. This would entail (though this is not part of this task) having a configuration for several users, such that they can setup this for themselves without others seeing their password.
This task doesn't have to be necessarily code, a comprehensive guide on how to do this by hand would also be sufficient (but not obsoleting the coding task).