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HylaFAX The world's most advanced open source fax server


This is a living list of frequently asked questions about the HylaFAX fax software system.

Your comments, additions and fixes to the FAQ are welcome: please send them to You can also give feedback on specific questions through links provided on each individual page. If you cannot find the information you need here or in the archives, please subscribe to the community mailing list and ask for help there.



What is HylaFAX?

See About HylaFAX for more information.

Where did HylaFAX/FlexFAX come from?

Sam Leffler, while working at Silicon Graphics (SGI), wrote a fax server for SGI's IRIX servers called FlexFAX and released it to the public in 1991. Sam and others worked for several years on FlexFAX, adding new features and porting the software to new platforms. In 1995 FlexFAX was renamed HylaFAX to avoid potential trademark issues. Sam eventually decided to leave the project to pursue other interests which, even with the best intentions of the HylaFAX developers, caused development to slow dramatically. In 1998 HylaFAX development was revitalized by the creation of, a central repository for HylaFAX development, downloads, documentation, etc. and the project remains very active to this day.

So, to answer the question: HylaFAX, nee FlexFAX, was born of Sam Leffler and through the hard work and contributions of many other people, has grown to become what it is today.

Some old newsgroup postings that may be of interest:

Original FlexFAX announcement (mirrored here)

Announcement of (mirrored here)

Why is it called HylaFAX?

The name of this software package is "HylaFAX", not "hylafax", "Hylafax", or anything else. Also, do not call this software by its old name "FlexFAX" because that name is a trademark of another fax product and the folks that own that trademark are possessive. Please also note that "HylaFAX" is a trademark of Silicon Graphics and it should be treated as such when used in documentation.

Regarding the name, it is derived from the word hyla which is defined as "Any of a genus of (Hyla) of frogs, especially the tree frog." Hence the logo found on the home page for this software.

Finally, please recognize that this is free software that represents the work of many people. The section of "Acknowledgements" lists those people that have made significant contributions.

Why should I use HylaFAX instead of some other fax package?

HylaFAX is designed to be very robust and reliable. The fax server is designed to guard against unexpected failures in the software, in the configuration, in the hardware, and in general use. HylaFAX uses an intelligent scheduling policy that attempts to recognize different types of failures and optimize retry attempts. An important design goal is that users must never worry about transmit jobs being lost or mishandled: jobs are either completed successfully or the submitter is notified what happened to their job and why the job failed. If you are willing to shepherd your facsimile transmissions then other software packages may be more suitable for you.

HylaFAX supports a wide variety of modems and is designed to support any Class 1, 1.0, 2, 2.0, or 2.1 modem without modification to the source code. If you have a modem that provides only a Class 1 interface then HylaFAX is likely to be the only freely available software package that will work with your modem.

HylaFAX supports multiple modems and heavy traffic load. If you expect to send or receive more than 1 or 2 facsimile a day, then HylaFAX is likely to be the best package for you to use.

HylaFAX is expressly designed to be highly configurable without modification or access to the source code. The software comes with extensive documentation to assist in understanding how the software functions and how to configure it.

HylaFAX is freely available. There is no GNU copyleft policy. There are no requests for remuneration, constraints on use, or constraints on incorporation into products (compare this with other "freely available fax packages"). There are binary distribution packages or other formats for several Unixes.

Which modems can I use with HylaFAX?

HylaFAX is intended to be used with fax modems. Fax modems are not the same as data modems though most contemporary data modems also include support for fax communication. HylaFAX should work with any Class 1, 1.0, 2, 2.0 or 2.1 fax modem. Wherever possible HylaFAX works around known modem problems or restricts modem usage in order to provide a functioning system.

See Handbook:Choosing a Modem for more information.

What machines does HylaFAX run on?

HylaFAX is intended to run on any UNIX system that supports a particular set of features: FIFO special files, BSD-style sockets and the TCP/IP communication protocols, BSD-style file locking (flock) or equivalent functionality from which it can be emulated (fcntl, lockf), and POSIX 1003.1-style interfaces, including termios for manipulating tty devices.

The following systems are known to have these features: AIX v3.x, v4.x BSD/386, FreeBSD, HP-UX 9.x, 10.x IRIX, ISC4.0, Linux, OSF/1 V1.3 and V3.0, SCO 3.2v4 with TCP/IP, SCO ODT 3, SCO 5.0, Solaris 2.x, SunOS 4.1.x, SVR4.x on an Intel x86 and MIPS (UnixWare, Onsite, SINIX, ...), Ultrix 4.4.

How to tell which HylaFAX version you have?

If you need to refer to this specific software, you should identify it as:

HylaFAX v<version><n>

where <version> is found in the file VERSION and <n> is the number recorded in dist/hylfax.alpha. This string is also prominently displayed when you run the configure script to setup the software for compilation and each time the faxq scheduler process is started (look in the file where syslog messages are recorded).

What documentation is available?

HylaFAX™ comes with extensive documentation in two forms: this HTML-based documentation that is designed for on-line use and general guidance, and a complete set of UNIX manual pages that contain reference information in a more terse but precise format. The HTML documentation contains links to the manual pages providing a complete hypertext connection between the two forms of documentation.

The HylaFAX documentation is intended to support users of binary distributions; it is complete enough that access to the source code is not needed.

How should I report bugs?

Unconfirmed HylaFAX bugs and related questions should be sent by mail to the HylaFAX mailing list

Confirmed bugs and discussion items regarding security or technical-level matters should either be sent by mail to the HylaFAX development mailing list or posted directly to HylaFAX Bugzilla,

When corresponding about the software please always specify:

  • What version of HylaFAX you have
  • What compiler (including version) your are using
  • What system you are running on: system type and OS version
  • What kind of modem and the modem firmware revision
  • A description on how to reproduce the problem
  • A minimal trace log that shows your problem

For example: "HylaFAX v4.0pl2 under Solaris 2.3 with gcc 2.7.2; ZyXEL 1496E with 6.11a firmware."

Do not send large trace log or PostScript files to the mailing list; the list is quite large.

Do not send traces with binary i/o or timer tracing.

Do not send traces without time-stamps and do not remove lines in the trace.

Can I run HylaFAX on my NT/Windows Server?

Date: Tue, 10 Dec 1996 07:49:56 +0100 (MET) From: Matthias Apitz < > Subject: Re: HylaFax

>Mark Bradley wrote:

>Can I run HylaFax on my NT 4.0 Server? >S.Mark Bradley >Compucare Services

NO. (NT is not the answer, it's the question and the answer is NO :-))


Is HylaFAX able to receive/send 1000s of faxes/day?

Yes. When HylaFAX is described as "Enterprise Class" we mean it. The software itself is more than capable of handling the most demanding fax traffic requirements; 96 channels per server is routinely achieved. For high-density fax servers it is recommended to look at digital (TE/E1) fax boards.

Building From Source and Installation

Which Linux distributions contain HylaFAX?

Please see (and contribute to) the Distribution List.

Sending Faxes

How do I print a watermark on my faxes?

Thorsten Garrels wrote:

> I'd like to have a kind of "static" graphic in the background of every
> page hylafax sends. This could be a company-logo, for instance but as
> well a complete "letter-template". Instead of printing the text via a
> printer on this template you should be able to "print" your text
> directly on a virtual paper which already contain the company logo and
> locations.

Date: 13 March 2000 18:46
From: Frank Terhaar-Yonkers <>
Subject: Re: flexfax: background graphic for every sent page

What you want is a "watermark." This little postscript snippet prints CONFIDENTIAL diagonally across the page:

/wp$y 792 def
/wp$x 612 def
%-------Customize Here-------
/font /Helvetica-Bold def
/pointsize 96 def
/text1 (CONFIDENTIAL) def
%-------End Customization----
/center {dup stringwidth pop
2 div neg 0 rmoveto} def
wp$x 2 div wp$y 2 div pointsize 2 div sub moveto
.85 setgray
font findfont pointsize scalefont setfont
45 rotate
0 0 text1 center ashow

Merge something like this (a exercise left to someone else) with the postscript sent to Hylafax.

- Frank

How do I keep private information off the cover page?

To keep private information off of the fax cover sheet and out of the publicly displayed information (such as the queue listings shown by faxstat) you need to create a dialrules file that's used on systems where HylaFAX client applications are run.

For example, if calling card information is specified as a trailing comma-prefixed number string (perhaps with trailing whitespace) then the following rules would strip it off when creating an displayable representation of the dial string:

DisplayNumber = [
 ",[0-9]+[ 	]*" = ! strip calling card info and trailing ws

You can use the dialtest program to test the new rules.

If you don't use sendfax to submit your faxes, you will have to look in your submitting software manual for how to set this.

Note that on the server the session logs must be protected to insure the complete dialstrings are not readable by normal users. This is done using the LogFileMode configuration parameter; e.g. LogFileMode: 600 # protect logs with calling card info

Why are my faxes failing with "Kill time expired"?

The default kill time of a job is 3 hours. If HylaFAX can't send a fax before that deadline, it is rejected. There are two major reasons for this to happen:

  • No faxes are being sent at all. This is generally because faxgetty is not running and you didn't use faxmodem so HylaFAX has no modem available to send the job. The solution is to start faxgetty.
  • You sent a big batch of faxes and some were rejected with this reason. You need to set a bigger killtime for the job if you want to send big batches of faxes. With sendfax, it can be set on the command line with -k as in sendfax -k "now + 7 days" or in hyla.conf (or sendfax.conf) with KillTime: "now + 7 days".

This setting in hyla.conf only applies to the clients that come with HylaFAX (faxmail, sendfax). Overwrite Client-settings with Per-job Controls (JobControl).

Why are my faxes failing with "Blacklisted" errors?

Some countries have legislations requiring modem manufacturers to ensure modems can't dial a failed number too often in a short period of time. Even busy numbers may count toward the blacklist in some countries.

Some modem have commands to either disable blacklisting or to clear the blacklist table. You can try one of the following dialing commands in your device config file:

ModemDialCmd: AT%%TCBDT%s [for Rockwell/Conexant modems]
ModemDialCmd: AT%%T21,1d,0DT%s [for Lucent/Agere modems]
ModemDialCmd: AT%%D0DT%s [for TOPIC chipset modems]

If none of those are applicable, you can configure your modem with a different country setting, one that doesn't blacklist numbers. If the dial tone in use in your country differ from the one your modem is configured to use, it may be unable to detect dialtone. Changing the dialing command to add X3 should bypass this problem:

ModemDialCmd: ATX3DT%s

Some modem can have their blacklist cleared with an AT command, while others require the modem to be power cycled.

Why are my fax sends failing with 'textfmt: No font metric information found for "Courier-Bold"' (or similar)

You need the afm-tar.Z file for the Adobe Font Metric (AFM) fonts required by the sendfax program. You can get this file via FTP from Some HylaFAX distributions do not include these Metric files. A subset of these fonts is available via FTP from in the file If you do not install the AFM files into the location specified in the "FontPath' directive in your hyla.conf file, you get error messages about fonts not found. You can uncompress the file with 'uncompress'.

Receiving faxes

receive faxes

You can find a list of fax viewers at Fax Viewer Software.

Another possibility is to convert the received fax to PostScript or PDF and use a PostScript/PDF viewer.

I have trouble viewing faxes received in JBIG format

Newer versions of HylaFAX can receive faxes in JBIG format, yet tiff utilities may not be able to do anything with such faxes (libtiff needs to be patched to support JBIG faxes). No tiff viewer are known to be able to read such files either.

You can disable JBIG support by setting "Class1JBIGSupport: no" in your modem config file until you have utilities to work with JBIG tiff files.

See for more information on this.

Running a HylaFAX Server

"Service not available, remote server closed connection?"

> After running
> faxmodem to setup my modem, I run faxstat to make sure that it's up, and
> receive the following msg:
> Service not available, remote server closed connection
> Telneting in to the machine on port 4559 gets a "Connection closed by
> foreign host." message.

Looks like hfaxd(1) isn't running on your machine. You have to make sure that hfaxd(1) and faxq(1) is running before you get any decent response with faxstat(1).

Do I have to restart a server after changing the modem config file?

No. The HylaFAX servers will re-read a config file (if needed) before each send and on any reset. This means you only need to explicitly restart a server if you change it before doing a receive. You can also avoid restarting it if you use cu/tip to talk to the modem since this will cause the server to wakeup and then reset itself when you exit from cu/tip.

How do I suppress or amend the "Fax Usage Report" which is emailed to FaxMaster daily?

Chances are you've installed a HylaFAX package, such as an RPM, that has set this report up as a cron job. On Red Hat, look at /etc/cron.daily/hylafax, and comment out the faxcron line. Each package/distro will be different, but the genral process is the same - find the cron job and deactivate (or customize) the running of it.

What hardware is supported by HylaFax?

That's hard to answer. Most Class 1, 1.0, 2, 2.0, and 2.1 fax devices will work with HylaFAX with varying levels of success. You can get a relatively good idea of the best hardware to use with HylaFAX via the Hardware Compatibility List or at


Is support available for HylaFAX?

There are many support options, both free and commercially provided. Please see the Support page for more information.

Why are all my received TIFFs corrupted?

If you're not able to open received TIFF files and when you try to convert them to ps using tiff2ps or fax2ps, you get errors like:

Fax3Decode2D: fax00013.tif: Bad code word at scanline 0 (x 89).
Fax3Decode2D: fax00013.tif: Uncompressed data (not supported) at scanline 0 (x 0).
Fax3Decode2D: Warning, fax00013.tif: Premature EOL at scanline 0 (got 89, expected 1728).

Check the verison of libtiff you're running. If it's 3.6.0 or 3.6.1, this may be your problem.

Solution: Downgrade libtiff to 3.5.7.

Why do faxes sometimes go to the wrong number?

One possibility is that you have another device on the same line that tried to call that wrong number just before HylaFAX tried to send it's fax. When HylaFAX dialed its number, the call was already dispatched to the wrong number and the tone sent by HylaFAX's modem did nothing (they may make the other device to hang up). Then when the party called by the other device answered, the call was established with HylaFAX and you get a fax sent to the wrong number.

There exist line sharing devices that you can use so that this won't happen. The device gives a busy signal when the line is already in use by another device.

How to fix HDLC errors with t38modem?

Not all versions of t38modem use the default Class1FrameOverhead of 4 (which is normal for a modem correctly implementing the Class 1 interface). Try adding the following line in your device config file:

Class1FrameOverhead:   2

If you already have this line, try commenting it.

Why aren't emails being sent when using faxrcvd while the command line works?

Your rights setting for sendmail is probably incorrect. This means that your group rights doesn't change to smmsp and you therefore don't have rights to /var/spool/clientmqueue. Check the sticky bit for the group used by the sendmail program.

/usr/sbin/sendmail may point to /etc/alternatives/mta which probably points to /usr/sbin/sendmail.sendmail

ls -l /usr/sbin/sendmail.sendmail should list

-rwxr-sr-x ? root smmsp ???? ?? ???? /usr/sbin/sendmail.sendmail

If the s bit is not set or group is not smmsp then use following commands.

chgrp smmsp /usr/sbin/sendmail.sendmail

chmod g+s /usr/sbin/sendmail.sendmail

Notification messages with other languages (I18N)

To change the language in the e-mail notification messages from the server you can do the following (since version 4.3.0).

Edit the files


write the line:


(as example for german language). That replace the path-var $TEMPLATE in the scripts.

The file ./FaxDispatch you can read in the faxrcvd man page.

In the /var/spool/fax/etc/templates directory resides the language specific subdirs. Here you can change whatever you want. Note: make a backup before change!

Sendpage - SMS & Pager Gateway

The log shows that the SMS is sent correctly, but it never gets delivered to the addressed cell phone

Check for trailing spaces in the pagermap file

When calling the SMS Call Center (D1, D2, E-plus) I get an 'No initial ID response paging central'

Check the file for the Call Centers Number in hylafax info dir, there should be an option &pagerTTYParity:"none" in there if there isnt add it and try again

When calling D2 I get an 'No initial ID response from paging central' but I have added &pagerTTyParity:"none" to the file in info

Check if you have added &pagingProtocol:"ucp" to the info file

The call center is rejecting my messages Blocks

Check if you are really sending plain ASCII files, this happened to me when working with templates generated on an windows box and it turned out the templates weren't plain ASCII

Does HylaFAX support the UCP protocol for SMS?

Yes. See hylafax(1):

Support is provided for transmitting alpha-numeric mes-
sages to pager devices or GSM mobiles using the  Simple
Network  Paging Protocol (SNPP) and the IXO or UCP pro-
tocol (for message delivery).

Is there an application to redirect emails to pages?

Date: Tue, 1 Oct 1996 15:01:55 -0600 (MDT)
From: Jason Kohles <>
Subject: Re: Sendpage and Mail

On Tue, 1 Oct 1996, Ravi Pina wrote:

> Is there a mail2page application that exists where there is an alais
> setup to redirect mail messges to pages?

I use filter (the mail filtering software that comes with elm) with a filter like this:

### email pager - bitchin
if [ SUBJECT CONTAINS "URGENT" ] then executec "/usr/local/bin/sendpage 

this sends "MP: the subject line" to my alpha pager.

Jason Kohles -- System Administrator -- XMission Internet Access (at work) (at play)

Email to Fax

How do I setup HylaFAX as an email-to-fax gateway?

(An Email to Fax Gateway allows a user to send an email to a predefined email account which then processes and faxes out the document through a fax modem.)

See the HylaFAX Handbook's section on Email-To-Fax.

Which document types can I fax using HylaFAX's email-to-fax capability?

By default faxmail, HylaFAX's email-to-fax gateway application, supports plain text and Postscript attachments. Faxmail also includes the ability to use external processors for other document types. Please see the faxmail man page for more information.

Fax to Email

How do I setup HylaFAX as an fax-to-email gateway?

For a simple example see the faxrcvd man page.

Miscellaneous Stuff

Is there a way to integrate Asterisk and HylaFAX?

Your best option presently is to use Lee Howard's IAXmodem with Steve Underwood's spandsp library. For more information, see:

See also a nice detailed howto here:

How can I fax Microsoft Office files?

One way to easily fax Windows files is by using a HylaFAX Windows client. Please see the Client Software page for a complete list of free and commercial clients.

How can I improve the resolution quality of incoming faxes?

This page was last edited on 2 November 2016, at 13:32.

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