Some files contain lines that begin with the five characters "
From
" (the fifth character is a space). What happens to such lines when the files containing them are delivered to a local mailbox? What UNIX utilities are available to aid in sending such a file with those lines intact?
In the file
sendstuff
, we created a one-line header that began with
Subject:.
What would be the effect of making that header all lowercase? What does RFC822 have to say about this? (See "Additional Sources of Information" in the Preface.)
How does sendmail behave when it is given a message that contains only a header? Does it add a blank line to create an empty body?
If your MUA supports a
-v
(verbose) command-line switch, try to send mail to someone at a remote machine using that switch. You should be able to observe the actual conversation between your local
sendmail
and a remote machine's
sendmail
.
If you can, send mail addressed both to yourself on the local machine and to yourself on a remote machine. Compare and contrast the header part of each.
If you are at all fuzzy about the concept of envelope, review Section 1.7, "The Envelope" now. We will refer to envelopes often throughout this tutorial.
Leap ahead to Chapter 35 for additional information about specific headers.