Linux Network Administrator Guide, Second Edition

rewrite: ruleset  96 returns: isaac < @ vstout . vbrew . com . >
rewrite: ruleset   3 returns: isaac < @ vstout . vbrew . com . >
rewrite: ruleset   0   input: isaac < @ vstout . vbrew . com . >
rewrite: ruleset 199   input: isaac < @ vstout . vbrew . com . >
rewrite: ruleset 199 returns: isaac < @ vstout . vbrew . com . >
rewrite: ruleset  98   input: isaac < @ vstout . vbrew . com . >
rewrite: ruleset  98 returns: isaac < @ vstout . vbrew . com . >
rewrite: ruleset 198   input: isaac < @ vstout . vbrew . com . >
rewrite: ruleset 198 returns: $# local $: isaac
rewrite: ruleset   0 returns: $# local $: isaac

Again, this test passed. Next we'll test mail to our UUCP style address: vstout! isaac.

# /usr/sbin/sendmail -bt
ADDRESS TEST MODE (ruleset 3 NOT automatically invoked)
Enter <ruleset> <address>
> 3,0 vstout!isaac
rewrite: ruleset   3   input: vstout ! isaac
rewrite: ruleset  96   input: isaac < @ vstout . UUCP >
rewrite: ruleset  96 returns: isaac < @ vstout . vbrew . com . >
rewrite: ruleset   3 returns: isaac < @ vstout . vbrew . com . >
rewrite: ruleset   0   input: isaac < @ vstout . vbrew . com . >
rewrite: ruleset 199   input: isaac < @ vstout . vbrew . com . >
rewrite: ruleset 199 returns: isaac < @ vstout . vbrew . com . >
rewrite: ruleset  98   input: isaac < @ vstout . vbrew . com . >
rewrite: ruleset  98 returns: isaac < @ vstout . vbrew . com . >
rewrite: ruleset 198   input: isaac < @ vstout . vbrew . com . >
rewrite: ruleset 198 returns: $# local $: isaac
rewrite: ruleset   0 returns: $# local $: isaac

This test has also passed. These tests confirm that any mail received for local users on this machine will be properly delivered irrespective of how the address is formatted. If you've defined any aliases for your machine, such as virtual hosts, you should repeat these tests for each of the alternate names by which this host is known to ensure they also work correctly.

Next we will test that mail addressed to other hosts in the vbrew.com domain is delivered directly to that host using the SMTP mailer:

# /usr/sbin/sendmail -bt
ADDRESS TEST MODE (ruleset 3 NOT automatically invoked)
Enter <ruleset> <address>
> 3,0 [email protected]
rewrite: ruleset   3   input: isaac @ vale . vbrew . com
rewrite: ruleset  96   input: isaac < @ vale . vbrew . com >
rewrite: ruleset  96 returns: isaac < @ vale . vbrew . com . >
rewrite: ruleset   3 returns: isaac < @ vale . vbrew . com . >
rewrite: ruleset   0   input: isaac < @ vale . vbrew . com . >
rewrite: ruleset 199   input: isaac < @ vale . vbrew . com . >
rewrite: ruleset 199 returns: isaac < @ vale . vbrew . com . >
rewrite: ruleset  98   input: isaac < @ vale . vbrew . com . >
rewrite: ruleset  98 returns: isaac < @ vale . vbrew . com . >
rewrite: ruleset 198   input: isaac < @ vale . vbrew . com . >
rewrite: ruleset 198 returns: $# smtp $@ vale . vbrew . com . /
    $: isaac < @ vale . vbrew . com . >
rewrite: ruleset   0 returns: $# smtp $@ vale . vbrew . com . /
    $: isaac < @ vale . vbrew . com . >

We can see that this test has directed the message to the SMTP mailer to be forwarded directly to the vale.vbrew.com host and specifies the user isaac. This test confirms that our LOCAL_NET_CONFIG definition works correctly. For this test to succeed, the destination hostname must be able to be resolved correctly, so it must either have an entry in our /etc/hosts file, or in our local DNS. We can see what happens if the destination hostname isn't able to be resolved by intentionally specifying an unknown host:

# /usr/sbin/sendmail -bt
ADDRESS TEST MODE (ruleset 3 NOT automatically invoked)
Enter <ruleset> <address>
> 3,0 [email protected]
rewrite: ruleset   3   input: isaac @ vXXXX . vbrew . com
rewrite: ruleset  96   input: isaac < @ vXXXX . vbrew . com >
vXXXX.vbrew.com: Name server timeout
rewrite: ruleset  96 returns: isaac < @ vXXXX . vbrew . com >
rewrite: ruleset   3 returns: isaac < @ vXXXX . vbrew . com >
== Ruleset 3,0 (3) status 75
rewrite: ruleset   0   input: isaac < @ vXXXX . vbrew . com >
rewrite: ruleset 199   input: isaac < @ vXXXX . vbrew . com >
rewrite: ruleset 199 returns: isaac < @ vXXXX . vbrew . com >
rewrite: ruleset  98   input: isaac < @ vXXXX . vbrew . com >
rewrite: ruleset  98 returns: isaac < @ vXXXX . vbrew . com >
rewrite: ruleset 198   input: isaac < @ vXXXX . vbrew . com >
rewrite: ruleset  95   input: < uucp-new : moria > isaac </
    @ vXXXX . vbrew . com >
rewrite: ruleset  95 returns: $# uucp-new $@ moria $: isaac </
    @ vXXXX . vbrew . com >
rewrite: ruleset 198 returns: $# uucp-new $@ moria $: isaac </
    @ vXXXX . vbrew . com >
rewrite: ruleset   0 returns: $# uucp-new $@ moria $: isaac </
    @ vXXXX . vbrew . com >

This result is very different. First, ruleset 3 returned an error message indicating the hostname could not be resolved. Second, we deal with this situation by relying on the other key feature of our configuration, the smart host. The smart host will is to handle any mail that is otherwise undeliverable. The hostname we specified in this test was unable to be resolved and the rulesets determined that the mail should be forwarded to our smart host moria using the uucp-new mailer. Our smart host might be better connected and know what to do with the address.

Our final test ensures that any mail addressed to a host not within our domain is delivered to our smart host. This should produce a result similar to our previous example:

# /usr/sbin/sendmail -bt
ADDRESS TEST MODE (ruleset 3 NOT automatically invoked)
Enter <ruleset> <address>
> 3,0 [email protected]
rewrite: ruleset   3   input: isaac @ linux . org . au
rewrite: ruleset  96   input: isaac < @ linux . org . au >
rewrite: ruleset  96 returns: isaac < @ linux . org . au . >
rewrite: ruleset   3 returns: isaac < @ linux . org . au . >
rewrite: ruleset   0   input: isaac < @ linux . org . au . >