When you install SCO OpenServer, you are given a choice of MMDF or SendMail as your Mail Transport Agent (MTA). To use the Internet Manager for configuring electronic mail, you must choose SendMail. SendMail gives you full access to multihoming and other advanced mail features not available from MMDF.
If you installed MMDF, but now want to use SendMail, use the Software Manager to remove the MMDF package, then add the sendmail package.
A Post Office Protocol (POP) server is configured at installation time so that many popular mail programs on PCs and Macintoshes (including Microsoft Outlook and other POP clients) can receive mail using your system as the server.
The system is configured so that any incoming mail destined for your system is either delivered locally (if the destination user exists) or is rejected; if the system receives any mail destined for another system, it forwards it on to that system. Any mail addressed to postmaster is delivered to the root user as well as to those users you have designated postmaster.
Outgoing mail is delivered directly to the system to which it is addressed. Mail sent by local users will have the fully qualified domain name of the system shown in the ``From:'' header (firstname.lastname@example.org, for example).
By clicking on the Mail button on the Internet Services page, you can change the configuration of e-mail forwarding and host hiding (what gets shown on the ``From:'' header for outgoing mail). If you have a central system that has a full user database for your domain, you can choose to forward ``local mail'' to that host. In addition, you can specify a system to which all mail outside your domain is delivered. It is intended that this system has good Internet connectivity and is well able to handle large amounts of SMTP traffic.