Configuring the Hostname

E-mail messages have names embedded in them. These names identify the computer, so in theory they should be the same as the computer's hostname. Sometimes, though, the names in the header may need to be changed. For instance, you might want outgoing mail to be associated with your domain name rather than with the mail server name. Configuring your mail server in this way can head off problems down the road—say, if you change your mail server system. If your outgoing mail had used the mail server's true hostname, replies to old messages might continue to be addressed to this system and, therefore, bounce. To set the name that's used in the From: headers in mail messages, you should add lines such as the following to the m4 configuration file and rebuild your main configuration file:

MASQUERADE_AS £ target-address?) FEATURE(masquerade_envelope)

Note The MASQUERADE_AS line includes two types of single quote characters. The lead character is a back-tick, accessible on most keyboards on the key to the left of the 1 key. The close quote is an ordinary single quote character, which is on the key to the left of the Enter key on most keyboards. If you use the wrong characters, these lines won't work.

Of course, you should change the target-address in these sample lines to the address you want to use, such as The MASQUE RAD E_AS line changes only the address displayed in the From: mail header line. It also changes this configuration only if the mail reader doesn't specify a different address. Many clients enable users to set arbitrary return addresses, and these values override whatever option you set in sendmail. The FEATURE(masquerade_envelope) line goes further; it overrides the settings users enter in their mail clients. You might use this option if you want to limit users' ability to set bogus return addresses in their mail readers.

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