FAQ for An Experiment in Remote Printing


Last revised - 27/8/96 - DPN

Section 1 - Introduction, sources of information

1.1: What is this all about?

The experiment is a project in outreach: to integrate the e-mail and facsimile communities. Working together, many sites cooperatively provide "remote printing" access to the international telephone network. This allows people to send faxes via e-mail. The general-purpose Internet e-mail infrastructure takes care of all the routing, delivering the message to the appropriate remote printer gateway in a manner totally transparent to the user.

1.2: Outreach? What are you really doing?

We believe that by providing easy access to remote printing recipients, enterprise-wide access is enhanced, regardless of kind of institution (e.g., commercial, educational, or government), or the size of institution (e.g., global, regional, or local). This approach to outreach allows an organization to make it easier for the "outside world" to communicate with personnel in the organization who are users of facsimile but not e-mail, such as the sales person, the university registrar, or the (elected) official.

The ease in which the Internet mail infrastructure can be used to provide this facility is (yet) another example of the power of a general-purpose infrastructure. Of course, as the experiment progresses, some of the things we'll be studying are economic and policy models that deal with issues such as accounting and settlement.

1.3: How can I keep informed?

There's a mailing list.

If you wish to add yourself to, or remove yourself from the tpc-rp mailing list, send a message to majordomo@aarnet.edu.au with text of the form:

subscribe tpc-rp address


unsubscribe tpc-rp address

i.e. normally just send
unsubscribe tpc-rp

However, if your mail address has changed since you subscribed, send a message such as unsubscribe tpc-rp myoldname@myoldaddress

** For general majordomo help, including a list of commands, send mail to majordomo@aarnet.edu.au containing the single word "help" - DPN ***

1.4: By the way, how can I get another copy of this FAQ?

This, and other information is available by sending mail to the following places, depending on what you would like to read:

     * Frequently-Asked-Questions: tpcfaq@info.tpc.int*
     * Coverage List: tpccover@info.tpc.int*
     * Mailing list contributions: tpc-rp@aarnet.edu.au
     * How to use list-server:  majordomo@aarnet.edu.au
     * Administrative questions: tpcadmin@info.tpc.int
* - Automatic Mail Servers


1.5: Aren't there any WWW pages?

Of course ;) Thanks to Peter Shipley's pioneering work in this area of the project, there is quite a nice web interface - have at look at:


Peter maintains his own (alternative) server at:


but when we last checked it was rather outdated.

2.1: What's the simplest way?"

Is this simple enough?

To: remote-printer.Arlington_Hewes/Room_403@

This will get automatically routed to a remote printer server, which will transmit a facsimile to the recipient. When the transmission completes, a message will be sent back to you.

2.2: Fine. What does this mean?

Let's look at the strings on either side of the '@'-sign.

The left-hand part identifies the kind of access (remote-printer) along with the identity of the recipient (Arlington_Hewes/Room_403).

Because some mailers have difficulty dealing with addresses that contain spaces, etc., you should be very careful as to what characters you use to identify the recipient. It safest to use upper and lower case letters, digits, and two special characters ('_' and '/').

When a cover sheet is generated, the '_' will turn into a space and the '/' will turn into an end-of-line sequence. So, given the address above, the cover sheet might start with

Please deliver this facsimile to:

Arlington Hewes
Room 403

2.3: What about the rest of it?

The right-hand part identifies the telephone number of the remote-printer. It must be an international telephone number. Telephone numbers are usually written like this:


where "code" identifies the country and "number" is the telephone number within the country, e.g.,

+1-415 968 2510

For those interested in telephonic trivia, the maximum number of digits is 15. In order to get the Internet e-mail infrastructure to automatically route messages, the punctuation characters are stripped out, e.g.,


and then the string is inverted and turned into an Internet domain name, e.g.,

Note that the telephone number should not include any international access codes. Here's why: if, from the US, I wanted to call someone in Tokyo (+81-33-...), I would dial something starting with "0118133" The first three digits (011) is the international access code for the US. If I were to call that same number from FR, I would dial something starting with "198133". The first two digits (19) is the international access code for FR. In contrast, the tail of the domain name for Tokyo is always

regardless of where in the world you are sending your mail.

This approach allows us to map from the Internet naming scheme onto the entire international telephone network. And, as you might expect, you can mix remote-printing and e-mail recipients in the same message, e.g.,

To: remote-printer.Arlington_Hewes/Room_403@

cc: Marshall Rose

In fact, the replies generated by the e-mail recipients can even go to the remote-printing recipients.

2.4: How much of the world is accessible via this experiment?

The official kick-off of the experiment was 16 July 1993. At that time, service was operational for:

    - Canberra, Australia (+61-62)
    - Washington, DC (+1-202)
    - most of Silicon Valley (+1-408, +1-415, +1-510)
    - parts of Riverside, California (+1-818, +1-909)
    - the University of Michigan (+1-313)

Since then, cells have been set up in the following countries:

    - Denmark
    - Finland
    - Japan
    - Sweden
    - England
    - Taiwan
    - Canada
    - Croatia
    - Portugal
    - Italy
    - New Zealand
    - Korea
    - Hong Kong

Enterprises, such as companies, universities, and government R&D centers, have also come on-line. The basic idea is that each participating site registers a "cell" indicating the portion of the international telephone number space that they are willing to provide access to. A cell can be a continent, a campus, a building, or a single phone number.

2.5: "Cells"?

Well, we call them cells. The idea is that there are really four kinds of participating sites:

    - neighborhood sites
    - regional sites
    - enterprise sites
    - personal sites

A neighborhood site is run by someone who provides access to any facsimile machine in its "local calling area". The idea being that metered access to this area is fairly inexpensive, and the site is willing to provide access as a part of their community spirit. Access to Silicon Valley was provided by several neighborhood sites before it was scaled back recently. The interesting thing to note is that neighborhood sites may choose to shrink or expand their cell, depending on factors such as demand and cost.

A regional site is basically just a large neighborhood site, usually providing access to an entire country or a large part of a country, such as an area code. The continent of Australia was an example of a regional site, although the initial coverage has been recently scaled back to certain localities only.

An enterprise site is run by a company that provides access solely to its own facsimile machines. They register exactly those telephone prefixes which apply to their enterprise. The University of Michigan is an example of this. Of course, a geographically-disperse enterprise such as a multi-national company could also do this.

A personal site is run by someone who provides access to exactly one facsimile machine, usually one that resides on their desktop. In this case, when the remote printer server gets the message, it will just deliver it to the owner of the desktop -- via e-mail.

Note that there can be overlapping remote printer servers for a given area. A personal site, for example, might be in the area served by a neighborhood site. Since the Internet domain name system always favors the longest match, the smaller site gets precedence for its own traffic

2.6: How can I find out if there is access to a particular number?

Assuming you are on a UNIX machine:

If fax number is 1-301-555-1212, you can either do % nslookup -query=MX


% nslookup -query=MX 13015551212.iddd.tpc.int

As long as the result is not sinkhole.tpc.int, the fax number should be under the coverage. The name after the exchange should be the fax server machine.

contributor - Frank Chen

** Users of Mac, or PC Operating systems may have similar DNS tools - DPN **

2.7: Suppose I want to send images instead of text?

Use MIME. MIME is the Internet-standards track technology for multi-media messaging. Remote printer servers support, at a minimum, the following MIME content types:

    - text/plain
    - message/rfc822
    - application/postscript
    - image/tiff
    - multipart

So, you might send something like the following:

To: remote-printer.Arlington_Hewes/Room_403@
MIME-Version: 1.0
Content-Type: application/postscript


2.8: Suppose I want a lot of information on the cover sheet?

You want a lot of things don't you? A MIME content-type has been defined for this. It's called application/remote-printing. Here's an example:

Content-Type: application/remote-printing

Recipient:      Darren Nickerson
Organization:   University of Oxford
Department:     New Chemistry Lab
Telephone:      +44 1865 275975
Facsimile:      +44 1865 271503
Email:          darren.nickerson@balliol.oxford.ac.uk

Originator:     Mr. Arlington Hewes
Organization:   The Phone Company - International
Department:     Administration
Telephone:      +44 1234 123456
Facsimile:      +44 1234 123457
Email:          tpcadmin@info.tpc.int

Any text appearing here would go on the cover-sheet.

To use this mechanism, the top-level content in your message must be multipart/mixed, and the very first content in that must be application/remote-printing. Also, if you use this, then the left-hand part of the recipient's address should just be "remote-printer".

2.9: Come on, you must have developed an easier address format!

Okay, you got us. . .

As soon as it became clear that the original addressing scheme of reversing the number and separating it by periods was going to be found overly cumbersome by many, we devised a new scheme which implements a DNS hack developed by Mark Turner. Now instead of sending to:
you can send it to:


2.9: Is there software to help me compose messages like this

Yes. See the section below on "Is there software available?".

3.1: Suppose I want to operate a remote printer server?

You need four things:

    - a computer on the Internet (UUCP/polling's OK too)
    - a fax modem and phone line
    - fax spooling software
    - "glue" software to pull it all together

You also need to agree to operate the cell in a fashion consistent with the policies associated with the tpc.int subdomain.

3.2: Is there a document describing the technical details?

Yes. See RFC 1486, "An Experiment in Remote Printing". It's available at the usual RFC repositories. In the future, there will probably be several documents, including one on policy.

3.3.1: Who sets policy?

The tpc.int subdomain is structured as a cooperative of the remote printer servers around the world. Policy for the subdomain is made in the time-honored tradition of hoping that things will run well enough on their own. In cases where additional guidance is necessary, a Board of Arbitration and Conciliation considers situations brought to it by the members and issues written opinions.

Initially policy was set by the two people who started the experiment, Carl Malamud of the Internet Multicasting Service, a non-profit organization, and Marshall Rose of Dover Beach Consulting, Inc. (Rose spends half of his time on openly available projects, of which this is one.) Now however, the task has fallen on the shoulders of Darren Nickerson, a PhD student in Oxford, England.

3.3.2: "What is this policy?

Ultimately, it's all about maintaining basic principles for the subdomain such as: functionality, fairness, cost recovery, performance, efficiency, security, and legality.

3.3.3: What did Malamud and Rose get out of this?

An indictment by a federal grand jury. Just kidding. Ha, ha. They were doing research on how to integrate special-purpose devices like G3 facsimile printers into the fabric of a general-purpose infrastructure like the global Internet computer network. Neither Malamud nor Rose profited from the project, though they sincerely hoped that operators in the tpc.int subdomain were able to recoup their costs, save consumers money, and maybe even make a healthy profit.

3.3.4: What does Nickerson hope to get out of this?

Well, gee. . . he's not sure. His interest was piqued by the possibility of subverting large telco corporations, and after setting up his own cell in Oxford, he decided to take a larger role in the development of the tpc.int subdomain. Let's see what the kid can do.

3.3.4: Is there any guarantee that my fax will get delivered?

No. For now, there's one simple rule:

It is perfectly acceptable to deny access on the basis of originator identity, but it is not acceptable to deny access on the basis of recipient identity

The reason for this is simple: if a site finds that some originator is acting in an abusive manner, then the site can deny access. But, when a site registers a cell, it agrees to provide access to every telephone number in that cell. Of course, it can always register a smaller cell.

3.3.5: What about privacy?

There are strict rules as to the kind of auditing information which a remote printer server may keep. Basically, this information is necessary for debugging purposes, e.g., if you send a message and don't get a completion or failure acknowledgement later on, the site providing access may need to check into it. Also, there are strict rules guaranteeing that the contents of a fax are secure and will not be monitored by the remote printer server operators. Having said this, it's only as secure as you consider e-mail to be ;)

3.4: "Who can I contact for administrative questions?

That would be Mr. Arlington Hewes (tpcadmin@info.tpc.int). Mr. Hewes is a busy man, so before sending a note to this mailbox, please consider whether the general discussion list (tpc-rp@aarnet.edu.au) mentioned earlier might not be a more appropriate forum.

3.5.1: Do I really need an IP-connected machine?

Not really. Technically, just about any computer on the Internet could run a remote printer server. However, we recommend that the computer have IP-connectivity, since this tends to make the service faster than with systems connected with polling mechanisms like UUCP. Still, the tpc.int subdomain is not picky and if you can provide service for an area that would otherwise not have it, welcome aboard! The more important requirement is that you have fax spooling software available for your computer.

3.5.2: "Is there software available?

Yes, have a look at http://www.tpc.int/devel_corner.html

You may have to try this site a few times, as nameserver timeouts getting to England from afar have been a problem in the past.

An openly available implementation can be found on

site: ftp.tpc.int
area: tpc/
file: rp.tar.Z

Be sure to retrieve it in BINARY mode, eh?

In addition, if you're running Innosoft's PMDF software for OpenVMS, then you can contact them at service@innosoft.com for the details. Also, if you're a vendor who adds support for remote-printing to your software, we want to hear from you.

3.5.3: What's in the openly available software?

It contains pointers to existing openly available software along with some "glue" software for BSD-derived UNIX systems.

For sites that want to run remote printer servers, there is support for both the openly available FlexFAX package and the Bristol Group's IsoFax product. FlexFAX has recently had a name change - HylaFAX is different enough that many of the scripts will have to re-written. If you have done this, Arlington Hewes wants to hear from you!

For sites that want to use remote printing, there are some scripts, primarily for MH users. If you are willing to contribute to the openly available software package, we'd love to hear from you. For example, we'd love to see Mac clients, a Z-mail macro, or a new LISP interpreter/mail agent written entirely in sendmail rewrite rules.

4.1: And what does TPC stand for?

Go rent the film "The President's Analyst", Paramount Pictures, 1967.

4.2: "And what's with the post horn for a logo?

Go read Thomas Pynchon's "The Crying of Lot 49", Harpers and Row (New York, 1986).

5.1: How do I contact a cell's operator?

Look at the message you received to see what system processed your FAX (i.e., the system from which the reject message was sent). Then send mail to postmaster@that-system.

For the NYC area, this will turn out to be postmaster@tink.com (aka bob@tink.com) --- me.

contributor - Bob Tinkelman

** Alternatively, try faxmaster@that-system. Cell operators are required to set up an alias for just this reason - DPN **

5.2: A message from the server comes back saying "unrecoverable error" or "local configuration error". What does this mean?

It could mean many things, but indicates a problem with the cell itself usually. You should contact the cell administrator (see 5.1)


5.3: We're considering setting up a cell. What benefit will there be for us?

What benefit will there be for whom? The Internet users: the benefit is that they can transparently send email to people who only have a fax machine. For the service provider that sets up the gateway:

- there are no direct benefits because it is difficult to charge the email originator for sending the fax. The problem is dual: administrative (how do you charge 10 cents to someone that just sent one fax from across the country or worse, across the planet); security related (given that plain email does not provide authentication of the originator, how can you be sure that you are charging the right person?)

- However your service provider can use the fax cover to make advertisements. These can be either sold to third parties, or this could be advertisements to the service provider itself. In fact ever since I setup my gateway for Lisbon, I've had several people call me up and asking how they could connect to the Internet directly - if I were a service provider this would have pleased me :-)

contributor - Pedro Ramalho Carlos

5.4: Okay, but how much will it cost?

The costs are not very high:

   + setting up and maintaining the gateway
   + local telephone connection costs (in the US this can be nil in some
	cases as I understand)
   + keeping up with "terrorists" that abuse the system to mass faxing and
	so on, and explaining this to the abused ones. (This is probably the
	largest cost, but I've been quite lucky until now)

contributor - Pedro Ramalho Carlos

5.5: Is this mailing list archived?

Try ftp.aarnet.edu.au:/pub/mailing-lists/tpc-rp-*

I've added a note about this to the mailing list info file so people will be told when they subscribe.

contributor - Andy Linton

5.6: How can I FAX images again?

One way, to fax an image is by converting it to PostScript and then sending it just like any other PostScript message (using Mime). There are a number of (bitmap) convertors to PostScript, one of them is pnmtops. So to send a GIF, you first convert it to ppm (giftoppm) and then this ppm to ps (pnmtops).

This should work, since all cells understand PostScript. The only caveat is that the size of the message sometimes is limited as well, either by your local mailer, a mailer in between you and the local cell or the local cell itself.

Other formats are not guaranteed to be understood by the local cell. You can of course always try to send a TIFF image (using Mime) since this is mentioned as well in the FAQ, but I have not tried it extensively yet and I think it didn't work when I tried it a year ago or so. You can also contact the local cell administrator and ask which formats are understood by its cell.

Contributor - Bart Swennen

1. Create the graphics with your favorite package.

2. Save it as a postscript file In Windows you'll be able to this from any application by "printing" the to file, using a Postscript Printer driver.

3. Verify that the Postscript file doesn't have very long lines (and especially from Windows, that it does not begin with Ctrl-D)

4. Send the file as an application/postscript MIME body part to the RP address...

Contributor - Pedro Ramalho Carlos

5.7: But Eudora doesn't seem to send postscript files correctly!

Thanks to all who helped with my PS faxing problems. The solution was that Eudora 1.4 does not send PS files intact with control characters. 1.43 works quite well for PS to tpc faxing.

Contributor - Rick Wintersberger

In Eudora, use the AppleDouble format for attachments, with "Always as Documents" unchecked. This should be your default setting for maximum interoperability with non-Mac MIME readers. This should cause the body part to be sent as application/postscript. I'll attach this test file here (a box with a diagonal line inside). I used "Level 1 Compatible" "ASCII" output with "Format: Postscript Job" (not EPS). I also have LaserWriter 8 v1.1 drivers.

Note that if you have fonts in your document and don't know what kind of printer the eventual output will be done on, you are better off including all fonts in the file (the default is to include none). This makes it bigger, but you are more likely to get results that match what you expect. If you use a lot of fonts, though, you can overwhelm a rasterizer and perhaps the document won't print at all, so be careful.

One other thing...naming the file with a .ps at the end should help foreign systems understand what they're getting. I don't think Eudora looks at filename extensions when sending. I think it does use them to set Mac type/creator pairs when receiving attachments, though.

In Eudora, use the AppleDouble format for attachments, with "Always as Documents" unchecked. This should be your default setting for maximum interoperability with non-Mac MIME readers. This should cause the body part to be sent as application/postscript. I'll attach this test file here (a box with a diagonal line inside). I used "Level 1 Compatible" "ASCII" output with "Format: Postscript Job" (not EPS). I also have LaserWriter 8 v1.1 drivers.

Contributor - Tom Maufer tom.maufer@gsfc.nasa.gov

Hardware for Remote Printing kindly provided by the folks at Netcentric Corporation - http://www.netcentric.com/

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