620Part VRunning ServersPreparing Your (Web site templates) SystemYou will need a
620Part VRunning ServersPreparing Your SystemYou will need a few common items for either configuration, starting with the properhardware. A personal mail server can easily run on a Pentium-class computer, although you may notice occasional slowdowns while incoming messages are beingscanned. Disk space requirements depend mostly on how much mail you want tohave room for, so plan on having a few gigabytes for the operating system (which willleave you plenty of extra, just in case), plus the amount of mail you want to store. The operating system should be installed with only the basic set of packages beforeyou begin these examples. Some general information about the installation is pro- vided in Chapter 9. Although the software described in this chapter works even ifyou aren t running Debian, the installation methods will not. If you don t have a sparesystem to act as a dedicated mail server, you can still use it as your workstation, although this is obviously recommended only for personal use. Network ConfigurationYour network settings should also be properly configured before you begin installingthe mail software. The exact requirements depend on the method by which mail willbe delivered to your server: .Direct deliveryis the method used by most traditional mail servers. DNSrecords tell remote servers that any mail addressed to your domain should besent to your server via SMTP. .Retrieval from a mail hostis also possible using an MRA (Mail RetrievalAgent) such as Fetchmail. This option can be used when you have a mailboxunder a shared domain but want to access the mail on your own server. Thiscan also be done in combination with direct delivery if you have both yourown domain and mailboxes under shared domains. Configuration of Fetchmail is explained in the Configuring Mail Clients section ofthis chapter. Configuring for Direct DeliveryFor direct delivery to function, the SMTP service (TCP port 25) must always beaccessible to the outside world through a fixed name in DNS. This name will be inthe form of an A (Address) record. A records allow DNS resolver processes to deter- mine the IP address associated with a specific name and are used by most of thecommon protocols on the Internet. A typical DNS A record looks something like this: bigserver.example.org IN A 1.2.18.12The first parameter, bigserver.example.org, is the label, and the second parame- ter is the class (INfor Internet, which is where most DNS records are found). The Aindicates the type, and the final parameter is the IP address associated with the label. Note33_
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