image\howbutt.gifUsing the mail server as a relay mail server

You can configure Corel LINUX as an open relay mail server. Open relaying lets your mail server accept and forward email for a domain that is not local to your mail server (not specified in the locals configuration file). For information about domains, see "Domain names." For example, an SMTP client connects to your mail server and makes the following request:

RCTP TO: <frankj@myaddress.com>

This command informs the mail server to send the email message to the myaddress.com domain. For information about the RCTP TO command, see "Using electronic mail protocols." If the myaddress.com domain is not on the mail server, you can configure Corel LINUX to accept the email message and forward it to its destination. In this case the mail server accepts the email message and returns the following reply code:

250 ok

If you configure Corel LINUX to reject relaying, the mail server rejects the email message and returns the following reply code:

553 sorry, that domain does not exist on this mail server

The domain name is only accepted if the domain of the email address, specified in the RCPT TO command, is listed in the rcpthosts configuration file. The location of the rcphosts configuration file is /var/qmail/control/rcpthosts. If you delete this file, then the mail server will accept email messages for all domain names. You can change the name of the rcpthosts configuration file rather than delete it.

If you configure Corel LINUX to be an open relay mail server, remote mail clients can use your mail server to distribute negative email messages, such as commercial email and unwanted personal email. This can result in your mail server being blacklisted by other mail servers. For information about a blacklist, see "Using the qmail configuration files."

Another negative effect of configuring your mail server as an open relay mail server is the increase in use of bandwidth. There is a direct relationship between the increase in use of bandwidth and slower network connections. All network connections operate slower as more bandwidth is consumed. For example, an HTTP client will not be able to connect to your Web site as fast if the networks bandwidth is being consumed at a high rate. For information about bandwidth. see "What is a network?"

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