computer science

Mail-11

Mail-11 is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Mail-11 rather than just read about it. In short: Mail-11 was the native email transport protocol used by Digital Equipment Corporation's VMS operating system, and supported by several other DEC operating systems such as Ultrix. It normally used the DECnet networking system as opposed to TCP/IP.

Key takeaways

Mail-11 belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Mail-11 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Mail-11 from memory before moving on to harder problems.

Reference excerpt

Mail-11 was the native email transport protocol used by Digital Equipment Corporation's VMS operating system, and supported by several other DEC operating systems such as Ultrix. It normally used the DECnet networking system as opposed to TCP/IP. Similar to Internet SMTP based mail, Mail-11 mail had To: Cc: and Subj: headers and date-stamped each message. Mail-11 was one of the most widely used email systems of the 1980s, and was still in fairly wide use until as late as the mid-1990s. Messages from Mail-11 systems were frequently gatewayed out to SMTP, Usenet, and BITNET systems, and thus are sometimes encountered browsing archives of those systems dating from when Mail-11 was in common use. Several very large DECnet networks with Mail-11 service existed, most notably ENET, which was DEC's worldwide internal network. Another big user was HEPnet, a network for the high-energy physics research community that linked many universities and research labs. Mail-11 used two colons (::) rather than an at sign (@) to separate user and hostname, and hostname came first.

Some example headers To: THEWAL::HARKAWIK A message to user HARKAWIK on a machine or cluster of machines called THEWAL. Note that under VMS, usernames were not case-sensitive and were usually shown in uppercase, but under Ultrix, usernames were case-sensitive, and most sites followed the unix convention of using lower case usernames. Names of machines on a DECnet network were not case-sensitive. Thus, the header above implies that the mail is going to a VMS system, but the one following implies the user is on a Unix system.

To: DS5353::tabak A message to user tabak on node DS5353. Probably an Ultrix system.

From: GUESS::YERAZUNIS "it's.. it's DIP !" 21-SEP-1989 10:28:38.87 To: DECWRL::"decvax!peregrine!dmi" CC: YERAZUNIS This message was sent to the gateway at DEC's Western Research Labs, one of DEC's main Internet gateways. From there, it was expected to travel via uucp, from host decvax to host peregrine to user dmi. Since the timestamp is present, this must be a copy of a message that has already been sent, but since the From address is still in Mail-11 form, the text above must be copied from the local CC of the message rather than from the version that went through the gateway. Unlike SMTP mail, mail readers did not support automatic signatures; many users developed the habit of changing their personal name setting to be some interesting or amusing quotation.

To: IN%"president@whitehouse.gov" The message is to be gatewayed to another network, in this case to the Internet SMTP protocol, and then delivered to the user president at the domain whitehouse.gov

To: HEPNET::TUHEP::SLIWA The message has to go through two machines. First, it is given to the node HEPNET, which then passes the machine to the node TUHEP, where it is then delivered to the user SLIWA.

From: "TGV::MCMAHON"@yoyodyne.com Mail from user MCMAHON on a machine or cluster named TGV, that was passed out of an Internet SMTP gateway by yoyodyne.com. This is one form the header might take from the recipient's viewpoint.

References

Worked examples

Example 1 — a first encounter with Mail-11

Start with the simplest possible case. Write down what Mail-11 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Mail-11 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Mail-11 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Mail-11

In research: Mail-11 appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Mail-11 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Mail-11 is common in secondary-school and first-year university syllabi. It links to neighbouring topics DEC software, Email, so understanding it makes those chapters shorter.
In everyday life: Look for Mail-11 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Mail-11 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Mail-11 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Mail-11 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Mail-11 in simple terms?

Why does Mail-11 matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Mail-11?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Mail-11.