From ZaInternetHistory
1
R H O D E S U N I V E R S I T Y
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C O M P U T I N G C E N T R E
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ADDRESS FORMATS FOR MAILING
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7 February 1989
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Contents
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1. Network Addresses, an Introduction
1.1. Basic Address Format
1.2. Upper-case, Lower-case
1.3. Other Addressing Formats
1.4. Mail Relays and Munging
1.5. Multiple Relays
1.6. Internet Domain Addresses
1.7. Finding Somone's Network Address
1.8. Others Finding Your Network Address
2. Sending Mail.
2.1. To Universities on the RSA Network
2.2. To an International Address (eg BITNET, INTERNET, UUCP)
3. Receiving Mail
3.1. From a University on the RSA Network
3.2. From an International Address
1 1. Network Addresses, an Introduction
-------------------------------------
1.1. Basic Address Format
-------------------------
An electronic mail address has at least two components, viz a
USER (ie the person) and a HOST (ie the computer at which the
USER receives mail). There might also be other components in
the address, and these will be explained later on.
The user and the host are typed in response to the 'To:' prompt
of the MAIL command. They are separated by an '@' sign.
Thus the address of 'someuser' who is to receive mail on
'anyhost' will be
someuser@anyhost
It is not necessary to specify the '@anyhost' if the recipient
is on the same host as the sender. This is not disallowed, but
is discouraged.
Example 1.1.1
-------------
An example of this is, say, a user whose username is ZZQW on
host RURES. The address of this user is:-
zzqw@rures
1.2. Upper-case, Lower-case
---------------------------
Note that it is normally not necessary to worry about upper-case
and lower-case letters in an address. However, you should check
with the recipient first, as it could be that a particular host
is very fussy.
1 1.3. Other Addressing Formats
-----------------------------
This form of addressing (ie user@host) as used at Rhodes
University is used by the universities on the RSA network. It
is based on IBM's RSCS protocol. It is also used on the ARPA
Internet and Bitnet, but on those networks the host names are
usually composed of several word separated by periods.
There are other types of addressing formats for certain
networks. For example, the UUCP addressing scheme uses a '!'
(rather than a '@') to separate the username from the hostname,
and reverses the order. A simple address looks like
host!user
Because of its appearance (particularly in more complex
addresses), this form of addressing is known as a 'bang-path'.
The order in which the user and host are specified is the
reverse of that for the '@' form. If you are mailing to someone
on such a network, you must convert the address into the form
used by the Rhodes University mailing system. When the message
is forwarded from Rhodes to the network that uses the bang path
form, it will be converted automatically.
1.4. Mail Relays and Munging
----------------------------
As mail networks grew and became interlinked, it became
necessary to specify the route that the message had to take
through so-caaled 'relays'. For example, some hosts would act
as relays between two networks (say between BITNET and UUCP).
Clearly, one of the functions of the relay host is to change the
addressing format as necessary. This process is called
'munging'.
When mail has to move from one network to another via a relay,
the sender might have to state this explictly. This depends on
the 'intelligence' of the network. So it may sometimes be
necessary to extend the 'user@host' form by adding some routing
information. The address to be used to send a message to
'someuser' at 'anyhost' via 'relayxx' is
someuser%anyhost@relayxx
A A
| |
+-------+---- Note the % @ format.
+-------------------------------------------------------+
| NB. The bang path form of this is |
| |
| relayxx!anyhost!someuser |
| |
| BUT DO NOT USE THIS FORM WHEN MAILING FROM THE RHODES |
| UNIVERSITY MAILING SYSTEM. |
+-------------------------------------------------------+
1 Example 1.4.1
-------------
A specific example would be the address of a user called JONES
on host STANFORD which is reachable via the relay host NEWYORK.
The address is:-
jones%stanford@newyork
The NEWYORK mailing system sees the user part of the address as
JONES%STANFORD. It is known to NEWYORK that no such user exists
on the NEWYORK host, so the address is munged. Starting from
the right, this 'username' (JONES%STANFORD) is scanned for the
first %-sign. This is changed to an @-sign, and the messages is
mailed out on the link that is connected to STANFORD. This
address is then JONES@STANFORD, exactly as would be used by any
other user on the STANFORD network.
1.5. Multiple Relays
--------------------
There are some networks that might be reachable only via two or
more relay hosts. This means that mail must be directed to the
closest relay first, and this relay must be directed to send the
message to the second relay, which then forwards the message to
the host.
Example 1.5.1
-------------
Suppose that SMITH is on host TEXAS which is reachable from the
STANFORD host, which in turn is reachable from the NEWYORK host.
There is no direct link from where you are to TEXAS or to
STANFORD. Use the following address to reach SMITH:-
smith%texas%stanford@newyork
At NEWYORK, the address is munged to read
smith%texas@stanford
At STANFORD, the address is munged to read
smith@texas
1 1.6. Internet Domain Addresses
------------------------------
Because this starts to get very complex, the Internet developers
have endeavoured to simplify matters. It is highly desirable
that addresses are identical on all networks. Given the numbers
of computers connected via networks, it is not possible to
distribute the complete set of addresses to every host. There
is therefore a system of "domains", and the addressing problem
is delegated to the domains. These domains can in turn create
subdomains, and delegate further the address resolution problem
into smaller chunks.
This leads to the concept that host names are not usually
represented by single words. They can look like
cornellc.ccs.cornell.edu
tuns.bitnet
f2.n490.z2.fidonet.org
vax.ftp.com
While this looks complex, it is much better than the
alternatives. Mailing systems can now be made 'smart', and can
find what is currently the best route to be used to send the
mail to any host, because the nameservers can be found very
quickly given the hostname. It is indeed a small price to pay.
The drawback at this stage is that it is not implemented on all
hosts on all networks. Hence, some addresses may still need
routing information, and the relay hosts as well as the final
host may (will?) have names that are peppered with periods.
1.7. Finding Somone's Network Address
-------------------------------------
Using smart mailers (really smart ones) it is possible to find
the network address of any individual on the major networks.
However, this is not the case at Rhodes, yet. You will have to
use whatever methods you can to find the network address of the
person to whom you wish to send a message. This is normally not
difficult, no more so than finding the postal address of this
person.
1.8. Others Finding Your Network Address
----------------------------------------
Understand also that others have a similar problem in getting
network mail to you. Rhodes is not known to the smartest of the
smart mailers (yet). So, just as you provide your
correspondents with your postal address, telephone number, P O
Box number, Fax number and the like, you should let them know
your network address.
A more detailed description of your network address is given in
the section dealing with 'Receving Mail'.
1 2. Sending Mail.
----------------
2.1. To Universities on the RSA Network
---------------------------------------
Sending mail to South African universities is straightforward.
At this stage, no relay host need be specified.
Example 2.1.1 (for RURES and RUPLA)
-----------------------------------
To send mail to 'x123023' at 'csirvm' use
x123023@csirvm
Example 2.1.2 (for RUPHYS)
--------------------------
To send mail to x123023' at 'csirvm' use
JNET%"x123023@csirvm"
2.2. To an International Address (eg BITNET, INTERNET, UUCP)
------------------------------------------------------------
To send mail to an international network address, you must mail
via the relay host RURES. This relay works out the route to be
taken to get to the specified address.
Here are some possibilities of how you would formulate the
address:-
Example 2.2.1 (for RURES)
-------------------------
To send mail to 'bill@vax.edu' use (preferably)
bill@vax.edu
or (not the preferred way)
bill%vax.edu@rures
Example 2.2.2 (for RUPLA)
-------------------------
To send mail to 'bill@vax.edu' use
bill%vax.edu@rures
Example 2.2.3 (for RUPHYS)
--------------------------
To send mail to 'bill@vax.edu' use
JNET%"bill%vax.edu@rures"
1 Example 2.2.4 (for RURES)
-------------------------
To send mail to 'bill%vax.edu@relay.cs.net' use (preferably)
bill%vax.edu@relay.cs.net
or (not preferred)
bill%vax.edu%relay.cs.net@rures
Example 2.2.5 (for RUPLA)
-------------------------
To send mail to 'bill%vax.edu@relay.cs.net' use
bill%vax.edu%relay.cs.net@rures
Example 2.2.6 (for RUPHYS)
--------------------------
To send mail to 'bill%vax.edu@relay.cs.net' use
JNET%"bill%vax.edu%relay.cs.net@rures"
1 3. Receiving Mail
-----------------
3.1. From a University on the RSA Network
-------------------------------------------
Your address from any of the computers linked into the RSA
University network is
your local Rhodes address (currently your username)
an @-sign
your Rhodes host computer
No relay hosts need to be specified.
3.2. From an International Address
----------------------------------
Your international address is composed of
your local Rhodes address (currently your username)
a period
your Rhodes host computer
an @-sign
the Rhodes Fidonet node address
The Rhodes Fidonet node address is
f19.n490.z2.fidonet.org
This must be put together in a standard network address format.
It is not possible to describe every combination of addresses on
all types of networks. All that will be given here is the
Internet format, as it is the most widely know. There are
probably no regular network users who do not know how to get
mail to the Internet.
If you advise your correspondents that this is your Internet
form of address, they should be able to get help locally to form
the specific address for their network.
Experience so far has indicated that mailing from parts of the
.EDU domain requires that the sender specify that mail should be
relayed via
relay.cs.net
This issue is very site-specific, and it is very foolish if not
impossible to lay down specific rules for any or all networks
and for any or all mailing systems. The necessity or otherwise
to specify relay points to get to an address in the '.org'
domain will be well-know by the support staff at the remote
site, as after all they have been using mail networks for many
years.
1 Example 3.2.1. RURES Users.
----------------------------
A user whose RURES username is ZZQR will have an Internet form
of address as:-
zzqr.rures@f19.n490.z2.fidonet.org
Example 3.2.2. RUPLA Users.
----------------------------
A user whose RUPLA username is ZZQR will have an Internet form
of address as:-
zzqr.rupla@f19.n490.z2.fidonet.org
Example 3.2.3. RUPHYS Users.
-----------------------------
A user whose RUPHYS username is ZZQR will have an Internet form
of address as:-
zzqr.ruphys@f19.n490.z2.fidonet.org
1 MAIL003 Ends