sendmail, 4th Edition

Is an Alias Bad?

In tracking down local delivery problems, it can be difficult to determine where the problem lies. If you suspect a bad alias, you can force aliasing to be skipped and see whether that causes the problem to go away:

% /usr/sbin/sendmail -n user < /dev/null

This tells sendmail to send an empty mail message (one containing mandatory headers only) to the recipient named user. The -n prevents sendmail from looking up user either in the aliases database or in that user’s ~/.forward. If user resolves to the local delivery agent, the message will be delivered, and you should therefore suspect an aliasing problem.

Other switches, such as -v (verbose) and -d (debugging), can be combined with -n to view the delivery process in more detail.