However in order to understand the technology involved better, we have to understand how various other forms of faxing work and how this form of faxing differs from them.

Originally, faxing meant sending facsimile, or a copy of a document, from one place to another through the telephone network using the agency of appliances known as fax machines. Fax machines include a scanner, a printer, and a modem. Document is first scanned by the fax machine. Then the image data resulting from the scan is converted into electronic pulses by the modem, so that they can be sent over the telephone network or Public Switched Telephone Network (PSTN) to give its proper name, to another fax machine. Receiving fax machine converts the pulses back in to data and recreates the scanned image of the document. Finally machine's printer will print the document.

When computers started using modems to exchange data with each other, it also became possible to send faxes directly from the computer, using software. First the document in the computer was printed to what is called a "software fax", meaning that document was converted into data that can be understood by a fax machine. Then the modem attached to the computer sent the software fax to the receiving fax through the telephone network. Receiving fax machine printed out the document in the normal way. Computers could also receive faxes if they were connected to the telephone line and relevant software was running at the time.

Direct faxing from computers did not become popular because they had to be always connected to receive faxes. However with the wide spread adaptation of internet this problem of connectivity was solved. Solution involves the use of a fax server or a gateway always connected to the internet and the telephone network to send and receive faxes. It is this method that is known as "fax 2 email".

Fax server receives the faxes from the telephone network and converts it into an image, usually in either TIFF or PDF format. This image along with an email containing details of the fax, such as sending fax number, time received, etc., are sent to the user's email address. To send a fax user sends the document along with the receiver's fax number to the fax server. The fax servers will then send the fax to the number through the telephone network.

Fax to email method is cheap since users can obtain the services of a fax server through a provider. They no longer need expensive special hardware, software or a telephone line, since they can receive and send the faxes through a normal internet connection using email. It also frees the users from being tied to the fax line since they can access email from almost anywhere. They will be able to receive faxes at any time even when they are not online.