System Administration 170 Getting Started Guide rpm -q sendmail Unfortunately, configuring sendmail can be challenging for any but the most rudimentary mail servers. The myriad capabilities and the obtuse configuration style of this program mean that you’ll need to do some serious study if you want to have it perform securely and to the limits of its capabilities. Two execellent references are provided at the end of this section. Two initial configuration files that you can refer to are the /etc/sendmail.cw file and the /etc/sendmail.cf file. Man pages for these files can give you some initial guidance. One common sendmail configuration is to have a single machine act as a mail gateway for all the machines on your network. For example, suppose that the main Internet gateway at your company, corp.com, handles all mail accounts. We can add the hostnames of other machines in the organization to the /etc/sendmail.cw file, in order to have mail sent to those machines captured by the main mail server corp.com. For example, we might add the following lines to sendmail.cw: # sendmail.cw - include all aliases for your machine. diamond.corp.com emerald.corp.com quartz.corp.com Then on the other machines (diamond, emerald and quartz), we would edit the / etc/sendmail.cf file to “masquerade” as corp.com when sending mail, and to for- ward any local mail processing to company.com. To do this, find the DH and DM lines in /etc/sendmail.cf and edit them: # who gets all local email traffic ($R has precedence for unqualified names) DHcorp.com # who I masquerade as (null for no masquerading) DMcorp.com With this type of configuration, all mail sent will appear as if it were sent from corp.com and any mail sent to diamond.corp.com or the other hosts, will be delivered to corp.com. See also this standard reference book on sendmail: • sendmail, 2nd Edition; by Bryan Costales & Eric Allman; 1050 pages; January 1997; O'Reilly & Associates; ISBN: 1-56592-222-0