Computing 205/406 & IT8
Tutorial #5
- What is your preferred electronic mail address at Bendigo? In general,
what is the format of an Internet email address?
- What is the general format of an RFC822 electronic mail message?
- The DATA operation in the SMTP protocol uses a "." on a line
by itself to indicate the end of the mail message. What do you
think happens if this occurs in the message?
- The SMTP protocol, like the FTP protocol, uses a 3-digit code
in all communications from the server. From the example given in
the lecture, can you generalise about the significance of the
first digit of this code? What about the second digit?
- What is MIME? Explain briefly how MIME works to send a file
(eg, a GIF image) as an email message. What is a MIME Multitpart
message?
- What is the Post Office Protocol (POP) used for?
- In the SMTP protocol, the sender uses the "Rcpt to:" operation to
specify the mail destination. What do you think happens if this
is different to the "To:" address in the message itself?
Practicals Exercise
- When you receive mail on the departmental systems, it is stored
in your system mailbox. This is a file in "mailbox format".
Examine your system mailbox and explain what "mailbox format"
looks like. In particular, how do you tell where one message ends
and the next begins?
- The "mail spooling" system on a Unix host can be examined using
the mailq command. Try it.
- OK, time for some experimental computer science. In the last question,
above, the problem of conflicting addresses was given. Try it yourself
(be sure to use a sensible From: address in the header so that the
mail system can reply to you), and see how the mail system on the
recipient computer handles it. Be aware that every
electronic mail transaction is logged on all systems, so you would
be well advised to stick to local hosts, and addresses of people
you know.
This tutorial is also available in PostScript format.
Phil Scott