HP-UX Mailing Services Administrator's Guide (B2355-91064)

Messages addressed to hosts in the nz domain are relayed to the host gw.dcc.nz. HP
recommends that you seek permission from the administrators of hosts not under your
own control before relaying mail through them.
MX Failures:
Several possible failures are associated with MX configuration:
• The name server query for MX records fails.
The query fails because no MX records exist for the target host or because the name
server is not running. You can set the TryNullMXList option in the
/etc/mail/sendmail.cf file if you want Sendmail to always try to connect to
the host to which the message is addressed.
If the query fails temporarily (that is, h_errno is set to TRY_AGAIN) the message
is queued. The possible values of h_errno are documented in the header file
/usr/include/netdb.h.
• Connection attempts to the hosts in the MX list all fail.
Sendmail reports the failure attempting to connect to the last MX host (that is, the
highest preference value) in the list that it tried. For example, with mail exchangers
configured as in the paf.edu example earlier, if the attempts to connect to bling
and wheo result in temporary failures, but the attempt to connect to munch fails
permanently, the message is returned as an error. If the attempts to connect to
bling and wheo result in permanent failures, but the attempt to connect to munch
fails temporarily, the message is queued.
• A host cannot deliver a message to another host for which it is a mail exchanger.
This failure is handled as a normal delivery failure, either by the mail exchanger
host or by the host sending to the mail exchanger.
Defining Queue Groups
You can define queue groups according to the selected criteria, and process each group
with custom settings. The rule sets then select the queue group to which the recipient
of a message must belong.
You can use the -q command-line option to specify which queue to display.
The Default Queue Group
Sendmail offers a method to define multiple queue directories and a method to group
them by function or speciality. Sendmail contains a special queue group called mqueue,
for compatibility with older versions of Sendmail. This is the default queue group. It
inherits all the properties of all the -q commands and all the queue options.
When you declare additional queue groups, they inherit all their properties from the
default group, unless you override a particular property with a specific equate. Table 1-4
The Sendmail Utility 29