If you have a dedicated IP address and don't have to worry about leaving your phone line connected all the time, this is no problem. You just have to set up NT or Win95 to automatically redial if the line gets disconnected. Your system is essentially on the Internet.
However, if you have a dialup PPP account with dynamic IP (what most ISP's provide), it is more complicated. You have do several things:
1) Set up Win95 or NT to automatically dial when your Notes server needs to connect to the Internet. Do this by testing it with MSIE or Netscape.
2) Configure the SMTP MTA. Test sending mail and see if Win95 or NT automatically dials up and sends mail to an Internet address.
3) Ask you ISP to save all your mail in a multidrop POP3 account at their site. Your ISP should virtual host your domain (company.com) and hold all mail going to it. Get a copy of POP3Fido and configure it to retrieve mail (this should cause Win95 or NT to autodial when needed).
If you use OS/2 or are having problems with step (1), it is easier to use a Windows-based proxy such as WinProxy. These proxies can be set up to automatically dial the Internet. An additional benefit of this method is that they will also give your company dial-on-demand access to the web or to Usenet newsgroups.
Notes R4.6 and R5 include dialup SMTP support via the ETRN command. However, it is not documented clearly that your ISP has to give you a static IP address and your ISP also has to support ETRN on their mail server.
The reason this is so complicated is that SMTP is a "push" protocol (in Notes parlance). One of the destination SMTP servers is always expected to be available. Usually, your ISP's will set up their SMTP server as a backup in case your system is down. If you bring up your connection "for long enough", the ISP's SMTP server will send all the mail it has collected for you, but this still requires a dedicated IP address. This technique is not as reliable as a "push" (outgoing mail via SMTP MTA), "pull" (via a POP3 account) technique.