4.4 Things to Try

• If you have access to two machines, kill the sendmail daemon on one, then send mail to that machine from the other using the -v (verbose) switch. What does this tell you about why it is important to always re\%start the daemon after you have killed it? How can you tell that a remote sendmail daemon has died?

• Using the -v switch, send mail to yourself. In the message body, include nothing but lines that begin with dots. Does the message get through intact?

• Begin forming the habit of routinely running mailq several times per day. Start to learn the many reasons that mail is queued rather than sent.

• Write a shell script that runs sendmail with the -bv (verify) switch to determine whether every alias in the aliases(5) file is good and print those that aren't. Be sure to filter the output so that good addresses (those marked as deliverable) are not printed.

• Read the online manuals for all the MUAs on your system, such as that for /usr/ucb/Mail. For which MUAs is it possible to indirectly run sendmail in verbose mode? That is, which will pass a -v command-line switch through to sendmail?