This feature is still offered, but as of
V8.10 it does nothing. Instead, beginning with V8.7
sendmail, you should either use the
service-switch file (ServiceSwitchFile) to control use of
DNS or compile a sendmail without DNS support (NAMED_BIND).
The V8.6 sendmail configuration files usually
assumed that you were using DNS to get host information. If you did
not have DNS available (for example, if you were on a remote UUCP
node), you could declare that fact:
This told sendmail to assume that DNS was not
available. It did this by ignoring any errors from DNS lookups. Note
that this was really only a minor fix because other features (such as
bestmx_is_local) used DNS anyway.
Note that the result of a hostname lookup failure differs depending
on whether DNS is used. If a hostname is looked up with DNS and not
found, the message is bounced. If a hostname is looked up with DNS
and there is some temporary failure, the message will be queued, and
the name will be looked up again later. If the host is looked up in
/etc/hosts and the lookup fails, the message
Note that this feature is deprecated, and might not appear in future
versions of sendmail.