courierfax - Send faxes via E-mail
The courierfax module (if enabled by the system administrator) sends
E-mail messages by fax. Addressing an E-mail message to the address
5558888@fax faxes a printed copy of the message to the specified phone
The ability to send faxes may be restricted, or not available. The
E-mail message may be a MIME-formatted message. All attachments are
concatenated and sent together in a single fax transmission.
courierfax only knows how to handle certain kinds of attached.
Obviously, trying to fax a voice .mp3 attaching is not going to work.
courierfax knows how to handle plain text, Postscript, and PDF MIME
attachments. courierfax might also know what to do with other kinds of
attachment, depending on some optional software installed by the system
administrator. courierfax may also be able to read GIF, PNG, and JPEG
Color images are converted to black-and-white.
Images are faxed with one image per fax page (limiting image sizes to
The message will be returned as undeliverable if courierfax doesn´t
know how to handle a MIME attachment. If the first MIME section in the
E-mail message is plain text, the text appears on the fax cover page.
The sender/recipient information for the cover page is taken from the
The default courierfax configuration tries to resend the fax for up to
eight hours, after which the message is returned as undeliverable. The
message will also be returned as undeliverable if the fax transmission
is interrupted. The return bounce will state how many pages were
"@fax" may also be followed by additional keywords that specify extra
Send a low-resolution fax.
Ignore any attachment types that courierfax doesn´t understand.
Send a cover page only. This is useful in limited situations, with
something like this in a dot-courier(5) file:
This .courier file faxes the contents of a message, sans any
attachments, immediately upon receipt in addition to saving the
message in the mailbox.
FAX TRANSMISSION RECEIPT
The sender will receive a fax transmission receipt if the sender
requests an ESMTP delivery status notification. This is the -N option
sendmail -Nsuccess 5556666@fax <messagefile
When using other mail software, consult the mail software´s
documentation for instructions on requesting ESMTP delivery status
ADDITIONAL DIALING OPTIONS
courierfax configurations that are generated by the webadmin tool for
North American environments usually restrict phone numbers to a
standardized ten-digit telephone number, so that the fax address is
always <aaabbbcccc@fax>, and courierfax silently performs any needed
conversion to dial the number (such as adding “1” or dropping the local
It is also possible to reconfigure courierfax so that it accepts any
telephone string and dials it without any preprocessing. If so, the
address may contain any combination of digits, letters “A”, “B”, “C”,
and “D”, representing the four extra dialing tones not normally
accessible from most telephone keypads, the symbols “*” and “#”, or the
Most faxmodems pause and wait for a secondary dialtone, before
dialing the rest of the number.
The dash is replaced by a comma in the dialing string. A comma
results in most faxmodems pausing for two or three seconds before
dialing the rest of the number. It is not possible to enter a comma
directly, because commas are used to separate multiple E-mail
addresses. Use dashes instead of commas in the dialing string.
courierfax replaces all dashes with commas before dialing the
Similarly, courierfax replaces all pluses with “@” characters
before dialing. An “@” characters results in most faxmodems waiting
for the line to be silent for five seconds before dialing the rest
of the number. It is not possible to enter a “@” directly as part
of the telephone number itself, for the obvious reasons. Use pluses
instead of “@”s in the dialing string. courierfax replaces all
pluses with “@” before dialing the faxmodem.
The slightly arcane configuration file, /etc/courier/faxrc, sets up
which dialing strings are valid. The default configuration file
contains judicious comments that explain all the parameters, and what
they do. The default configuration file disables courierfax by
rejecting all telephone numbers. The file must be edited in accordance
with the embedded instructions, in order to enable faxing.
Using webadmin is highly recommended. Upon demand, webadmin will
install a suitable configuration file for the North American numbering
plan, that receives all telephone numbers as ten-digit numbers, and
adds any required long distance prefix, or removes the local area code,
as appropriate. Or, webadmin will install a bare-bones configuration
file that dials any requested phone number, without any editing or
There is no good way to sleep until a modem lock is released, so we
poll every minute.