Mail to Fax gateway Introduction Many technologies exist allowing faxing straight from your worksta­ tion. Many are proprietary or OS specific. On the other hand, the electronic mail is now well established with open standards: Anyone can mail. A mail to fax gateway provides a global solution to the fax problem: Now anyone can fax, from anywhere, using any operating sys­ tem. A mail to fax gateway introduces a new problem: Now anyone can fax, from anywhere, using any operating system. The mail to fax gate­ way of Linuxconf is not a faxing system but a sophisticated gateway with many access control strategies giving you control on who may fax from where on your server. 11.. PPrriinncciipplleess Here is a basic explanation of how it works, from a user standpoint. 11..11.. HHooww ttoo mmaaiill There are three email address formats allowed to send fax. · phone@fax.your_domain This is the simple case. It lacks the ability to encode the recipient name on the fax front page. If you text do contain this information, all is well. · name@phone.fax.your_domain This format encode both the phone number and the recipient name. For example, many will encode an email-fax like this jacques.gelinas@999-9999.fax.solucorp.qc.ca This lets the fax gateway extract both the phone number and the full name, so a nice front page may be built. · alias@fax.your_domain Linuxconf lets you define a list of alias for fax. This is handy when a lot of people need to fax to the same person. 11..22.. TThhee aattttaacchhmmeennttss The mail to fax gateway will support email attachment and will try to convert them to formats managed by the fax engine you are using. Often a fax will be an empty mail with a nice attachment in postscript or any suitable format. 22.. SSeettuupp Configuring the mail to fax gateway involves few operations. Mostly for the mail to get through, there is some DNS work to do. And you must set you access control policies. 22..11.. DDNNSS mmaannaaggeemmeenntt You must provide the "email advertising" or MX records for the fax gateway. You need to add two pseudo hosts in your domain. Each host will contain a pointer to the fax gateway server in the email advertising section. · fax.your_domain This pseudo host takes care of directing the email-fax of the form phone@fax.your_domain and alias@fax.your_domain. · *.fax.your_domain This one takes care of the form name@phone.fax.your_domain. 22..22.. SSeettttiinngg sseennddmmaaiill The fax gateway must run sendmail. It does not need to be the official mail server of your company although there are some relations. See the "access control details" later in this help document. The email to fax gateway must at least be enabled before generating the sendmail.cf. Fill the dialog "mail to fax gateway/basic information". Check out the help screen. Generate the sendmail.cf (Linuxconf will tell you to if you forget). 22..33.. AAcccceessss ccoonnttrrooll The topic of this is to define who can fax where. The default is that noone can fax. 22..33..11.. AAcccceessss rruulleess aanndd ggrroouuppss The mail to fax gateway may use several criterions to accept or reject a request. A rule is one combination of criterion that may be reused to control access to the various fax zones and fax alias below. 22..33..22.. FFaaxx uusseerrss Some fax destination are only available to specific users. You define them here. 22..33..33.. FFaaxx zzoonneess A fax zone associate a fax rule with a phone area. 22..33..44.. FFaaxx aalliiaasseess A fax alias associates a name with a phone number and a fax rule. This lets users fax to a name instead of a phone number. 33.. AAcccceessss ccoonnttrrooll ddeettaaiillss As noted earlier, the email to fax gateway is universally available. Mail protocol has been designed to go through. Unless one pay attention, any mail to fax gateway is reachable from anywhere in the world. To make it worst, this is generally exactly what most people need. To cope with that the Linuxconf email to fax gateway supports various scheme to limit access to this facility. Here they are. 33..11.. LLooccaall ffaaxxeess Whenever a mail message goes through a mail gateway, a new line is added in the enveloppe of the mail. This line tell us which gateway managed the message and when each received it. By counting the number of "Received" lines in the enveloppe, the fax gateway can tell if the mail originated from the local network or not. Linuxconf proposes this as a strategy to differentiate faxes from the inside from faxes coming from the internet. 33..11..11.. LLooccaall ffaaxxeess aanndd tthhee iinntteerrnneett Beware that this is not 100% fool proof. If the email to fax gateway is visible from the internet, anyone can telnet to it and inject a message in it. This will look like a local fax. To make sure the concept of "local faxes" is meaningful, you need some firewalling mechanism isolating the fax gateway from the internet. This way, the only way to reach it from outside will be by using at least another mail gateway and this will be detected as a non local fax. 33..11..22.. TThhee ffaaxx ggaatteewwaayy iiss nnoott tthhee mmaaiill sseerrvveerr The email to fax gateway is not always the mail server of the organisation. It is simpler if it is though. If this is the case, the following solution may be used: · Select the fax gateway as the smtp server for the various email client you are using. This way it will receive all the messages first hand. It will be able to differentiate local message from the others. · Set the mail server of the fax gateway to your real mail server. This way, all messsages which are not faxes will be routed to the real mail server. 33..22.. FFaaxx uusseerrss You can define a list of users who can fax to various location. A user is identified by his email address. You can also enter his PGP public signature. With this, the email to fax gateway will be able to certify that a fax message really came from the fax user. You can selectivly tell if PGP signatures are needed for different fax destinations.