Email vs Fax: How Each Works, Compared

Email and fax are both ways to send documents, but they work in fundamentally different ways. Email sends digital files over the internet, while fax transmits a scanned image of a page over a telephone line. This article explains the mechanics of each, compares their strengths and weaknesses, and helps you decide which is right for your needs.

Background: From Analog to Digital

Fax technology dates back to the 1840s, long before the telephone. Early fax machines used a pendulum to scan a document and transmit its image over a wire. Modern fax machines, standardized in the 1960s, scan a page into a grid of black-and-white dots, encode those dots as audio tones, and send them over the public switched telephone network (PSTN). The receiving machine decodes the tones and prints the page.

Email, by contrast, emerged in the 1970s as a way to send text messages between computers on a network. It became widespread in the 1990s with the rise of the internet. Email uses a store-and-forward model: your message travels from your mail server to the recipient’s mail server, where it waits until the recipient retrieves it. Today, email can carry text, images, and file attachments.

How Fax Works

A fax transmission involves three stages: scanning, encoding, and transmitting.

1. Scanning: The fax machine’s scanner reads the document line by line, converting the light and dark areas into a grid of pixels. Most fax machines scan at a resolution of 200×200 or 200×400 dots per inch (dpi).
2. Encoding: The pixel grid is compressed using a run-length encoding scheme (like Modified Huffman coding). This reduces the amount of data to transmit.
3. Transmitting: The encoded data is modulated into audio tones and sent over a phone line using the ITU-T T.30 protocol. The receiving fax machine demodulates the tones, decodes the data, and prints the page.

Modern fax services often use “fax over IP� (FoIP), which converts the fax data into IP packets and sends them over the internet. However, the document is still transmitted as a fax image, not as an editable file.

How Email Works

Email uses a set of protocols to move messages across the internet. Here’s the simplified path:

1. Composition: You write a message in an email client (like Gmail or Outlook). The message includes a header (To, From, Subject) and a body.
2. Sending: Your client sends the message to your outgoing mail server using SMTP (Simple Mail Transfer Protocol).
3. Routing: The server looks up the recipient’s domain (the part after “@�) using DNS (Domain Name System) and forwards the message to the recipient’s mail server.
4. Delivery: The recipient’s server stores the message until the recipient retrieves it via POP3 (Post Office Protocol) or IMAP (Internet Message Access Protocol).

Attachments are encoded using MIME (Multipurpose Internet Mail Extensions), which allows binary files to be sent as text. The recipient’s client decodes the attachment and saves it as a file.

Comparing the Two: Speed, Cost, and Reliability

Speed: Email is generally faster. A typical email with an attachment is delivered within seconds to minutes. Fax transmission takes about 30 seconds to a minute per page, depending on the resolution and the speed of the fax modem (usually 14.4 kbps).

Cost: Email is essentially free if you have an internet connection. Fax requires a phone line, a fax machine or service, and paper and toner for printing. Online fax services cost a monthly fee but eliminate the hardware.

Reliability: Fax is often considered more reliable for legal and medical documents because it provides a confirmation page (a “transmission report�) and is harder to intercept than an unencrypted email. However, fax can fail if the phone line is busy or the receiving machine is out of paper. Email can be delayed by spam filters or server issues, but it’s generally robust.

Security and Legal Considerations

Fax is often used for sensitive documents like medical records and legal contracts because it transmits over a dedicated phone line, which is harder to intercept than an unencrypted email. However, fax is not inherently secure—anyone with access to the phone line could tap it, and fax machines often sit in shared offices where printed pages can be seen. Email, when sent without encryption, can be intercepted in transit. For secure email, you need to use encryption like TLS (which most major providers use) or end-to-end encryption like PGP.

Legally, faxed signatures are generally considered valid, but the same is true for email signatures under laws like the ESIGN Act in the US. The key difference is that fax provides a physical paper trail, which some organizations still prefer.

Common Problems and Misconceptions

Misconception: Fax is obsolete. While fax use has declined, it’s still widely used in healthcare, legal, and government sectors because of regulatory requirements and the perception of security.

Problem: Fax fails to send. Common causes include a busy line, a disconnected phone line, or the receiving machine being out of paper. Most fax machines will retry automatically.

Problem: Email attachments don’t open. This often happens when the attachment is too large (over the provider’s limit, usually 25 MB) or when the file type is blocked by security filters. Using a cloud storage link is a common workaround.

How to Choose: When to Use Which

Here are some guidelines to help you decide:

• Use email when: You need to send an editable document, you want to send to multiple recipients easily, you need a record of the message content, or you’re sending large files (via a link).
• Use fax when: You need to send a signed contract, you’re dealing with medical records (due to HIPAA in the US), the recipient doesn’t have email, or you need a transmission confirmation.
• Use an online fax service when: You want the convenience of email but the legal standing of fax. These services let you send and receive faxes via email or a web portal.

Frequently Asked Questions

Can I send a fax from my computer without a fax machine?

Yes, you can use an online fax service like eFax or HelloFax. These services let you upload a document, enter the recipient’s fax number, and send it. The service transmits the fax over the phone network. You can also receive faxes as email attachments.

Is email legally binding like a fax?

In most jurisdictions, email is legally binding if it can be proven that the email was sent and received. The ESIGN Act in the US and similar laws in other countries give electronic signatures the same legal weight as handwritten ones. However, some contracts may require a “wet� signature or a notary, which neither email nor fax can provide.

Why do hospitals still use fax machines?

Hospitals use fax because it’s compatible with their legacy systems, and it’s considered more secure than email. Fax transmissions are point-to-point and don’t go through multiple servers like email. Also, many healthcare regulations were written when fax was the standard, so it’s easier to stay compliant.

Can I send a fax to an email address?

No, a fax machine cannot send to an email address directly because they use different protocols. However, you can use a fax-to-email service that receives the fax and forwards it as an email attachment. Similarly, you can send an email to a fax number using an email-to-fax service.

Which is cheaper: fax or email?

Email is cheaper because it only requires an internet connection. Fax has costs for the machine, phone line, paper, and toner. Online fax services typically cost $10–$20 per month, which is still more than email but less than maintaining a physical fax machine.

What happens if a fax number is busy?

The fax machine will automatically retry after a few minutes. Most machines have a “redial� feature that retries up to a set number of times. If the line remains busy, the fax will fail and you’ll get an error report. You can then try again later or use an online fax service that queues the transmission.

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