- 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 "The Envelope" now. We will refer to envelopes often throughout this tutorial.
- Leap ahead to for additional information about specific headers.